U6e Kural Science ^mt0 

Edited by L. H. Bailey 



IRRIGATION AND DRAINAGE 



lTl^><^o 



mRIGATION AND DRAmAGE 



PRINCIPLES AND PRACTICE 

OF THEIR 

CULTURAL PHASES 



BY 



F\ H. KING 



Professor of Agricultural Physics in the University of Wisconsin; 
Aiithor of "The Soil" 



THE MACMILLAN COMPANY 

LONDON : MACMILLAN & CO., Ltd. 

1899 

All rights reserved 



TWO COPlfcs 
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U L. :.j ■ , - 

Register of Cc 








19477 

OPYRIGHT, 1899 





By F. H. king 



SECOND COPY, 



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^oiint {^Icagant {printer? 

J. Horace McFarland Company 
Hairisbiirgr, Ha. 



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PREFACE 

Most works on irrigation have been written 
from the legal or sociological standpoint, or from 
that of the engineer, rather than from the cul- 
tural phases of the subject. The effort is made 
here to present in a broad yet specific way the 
fundamental principles which underlie the methods 
of culture by irrigation and drainage. Distinc- 
tively engineering principles and problems, as such, 
have been avoided, and so have those of plant 
husbandry. The aim has been to deal with those 
relations of water to soils and to plants which 
must be grasped in order, to permit a rational 
practice of applying, removing or conserving soil 
moisture in crop production. The immediately 
practical i)roblems, from the farmer's, fruit-grower's 
and gardener's standpoints, with the principles 
which underlie them, are presented in as con- 
crete and concise a manner as appears needful 
to build up a rational practice of irrigation 
culture and farm drainage ; and the effort has 
been to broaden the conceptions of general soil 

(v) 



vi Preface 

management, even when neither irrigation nor 
drainage is practiced. 

Great pains has been taken to personally 
inspect the irrigation practices of both humid and 
arid climates in this country and in Europe, to 
gain a broader view of essential details, and to 
secure suitable illustrations, which are presented 
largely as photo -engravings, in the hope of getting 
closer to the spirit of the subject. 

Free use has been made of all available litera- 
ture on the subject, and credit is given throughout 
the body of the text to various writers and 
works. 

F. H. KING. 

University of Wisconsin, 
March, 1899. 



CONTENTS 

INTRODUCTION (pages 1-65) 
General Remarks on the Importance of Water 

PAGES 

Definition of irrigation and drainage — Importance of water*' 
in crop production — Plants adapted to intermittent 
watering — Variation in the capacity of soils for water — 
Adaptation of plants to soils of different water capacity 
— Variations in soils and in rainfall may make irrigation 
or drainage needful — Better aeration and deeper root 
feeding in arid soils — Explanations not entirely satis- 
factory 1-9 

The Advantages of Abundant Supply of Soil Moisture. — Large 
volumes of water generally needed — Part played by water 
in crop production — Relation to plant life — Relation to 
soil microbes — Rains and irrigation may start formation 
of nitrates by diluting soil moisture — Relation of drain- 
age to development of nitrates and soil fertility — Soil 
water dissolves ash ingredients of plant -food — Water 
causes oxygen, carbon dioxide and nitrogen to enter 
the soil 9-15 

Water only One of the Necessary Plant-foods. — Difference in 
value of water for plant-food — More water used than 
any other substance 15, 16 

Amount of Water Used hy Plants. — Relation of climate to 
water used — Treatment of soil affects amount of water 
used — Irrigation and drainage modify amount of soil 
moisture — Apparatus used in measuring water used by 
plants — Aims of the experiments — First trials with oats, 
barley and maize — Field results with maize — Changes 
of soil moisture in field — Experiments with oats and 
barley — Experiments of 1893 to 1896 10 38 

(vii) 



viii Contents 

77- . ,. . , PAGES 

VanaH07is tn the Amount of Water Used hy Plaiits.-Two 
years compared — Field and plant-house yields compared 
— Loss of water in a saturated air — Amount of water 

required to produce one ton of dry matter 39_4G 

The Mechanism, and Method of Transpmition in PUints.— 
Transpiration and breathing — Structure of barley leaf — 
Inevitable loss of water by evaporation makes demands 
large -Amount of air breathed by clover to secure the 
needed carbon — Changes in humidity of air over a clover 
field— Assimilation of carbon takes place only in sun- 
shine—Breathing pores in leaves — How stomata per- 
mit and prevent loss of water — Structure of breathing 

P^^^« 4G-54 

Mechanism by ichich Land Plants Supply Themselves icith 
Water.— F&rt played by roots — Essential features of 
roots — Only the newer portions active in absorbing 
moisture — How water is taken up — Rate of feeding 
slows down as thickness of film becomes less — Root 
hairs acid and may hasten solution of plant-food — Need 
of great extent of root surface — Distribution of roots in 
soil — How roots advai!^e through soil — The root -cap. . . . 54-65 

Part I 
IRRIGATION CULTURE 

CHAPTER I 

The Extent and Geographic Range of Irrigation 
(pages 66-90) 

TJie Antiquity of Irrigation .— In Egypt — In Assyria — By 

the Phoenicians- Early Grecian and Roman — In China ^ 
— In Mexico and Peru 66-72 

Extent of Irrigation.— In the Po valley — In Sicily — In 
Spain — In France — In Switzerland —In Belgium — In 
Denmark— In Austria-Hungaria — In Bavaria — In Eng- 
land—In India— In Ceylon — In Australia -In other 



Contents ix 

PAGES 

parts of Asia — In Algeria — In Egypt — In Cape Colony 
— In Madagascar — In the Hawaiian Islands — In Java — 
In South America — In the Argentine Republic — In 
Western United States — Amount of land irrigated 72-89 

The Climatic Conditions Under ivhich Irrigation Has Been 
Practiced. — Amount of rainfall where irrigation has been 
practiced — Distribution of rain with reference to the 

y growing season 89, 90 

CHAPTER II 

The Conditions which Make Irrigation Imperative, 
Desirable, or Unnecessary (pages 91-116) 

Objects of Irrigation. — To establish right moisture relations 
— To increase fertility — To change texture of soil — To 
build up low areas — For sewage disposal 91-94 

Tlie Least Amount of Water which Can Produce a Paying 
Crop. — Importance of the subject — Amount of water 
needed for wheat — Slow rate of evaporation from dry 
soil — Average yield of wheat as related to rainfall — 
Dry farming 95-101 

Like Amounts of Rainfall not Equally Productive. — Differ- 
ences in yield and in rainfall — Causes of differences . . 101-106 

Frequency ayid Length of Periods of Drought. — Abundant 
watering at short intervals needful — Type of rain dis- 
tribution—Ineffective rains — Length of rainfall periods 
in Wisconsin — Yield of crops compared with rainfall — 
Length of too long periods of no rain — Yields due to 
rainfall and to irrigation compared 106-110 

Conditions ivhich Modify the Effectiveness of Rainfall. — In- 
fluence of soil texture — Amount of moisture in soil • 
when growth is checked — Loss of water by percolation 
— Rapid percolation chief cause of poor yields — Supple- 
mentary irrigation helpful on light lands— Topographic 
conditions influencing effectiveness — Sub -irrigation may 
supplement rainfall 110-116 



^ Contents 

CHAPTER HI 

The Extent to which Tillage May Take the Place 
OF Irrigation (pages 117-170) 

PAGES 

The Insufficiency of Water to Irrigate all Cultivated Lands.— 
Discharge of the Mississippi river— Mean annual run- 
off for the United States — Proportion of cultivated 
fields which might be irrigated 117-120 

Most which may he Hoped for Tillage in the Use of Water.— 
Do soils take moisture from air to helpful extent ?— 
Tillage does not diminish transpiration in plants, and 
cannot dispense with water , 220 121 

TJie Amount of Main Needed to Produce Maximum Crops in 
Humid and Sub-humid Begions.— Acre-inches required 
for a pound of dry matter— The amount of available 
rainfall in the United States — Effective rainfall of 13 
states— Theoretical yields which may be expected 121-125 

TJie Distribution of Bain in Time Unfavorable to Maximum 
Yields.— Mean yields of barley, oats and maize in 13 
states — Small mean yields, due to unfavorable dis- 
tribution of rain 125-127 

Methods of Tillage to Conserve Moisture often Ineffective.— 
Cultivation inapplicable— Meadows and pastures— Mean 
yield of hay in 13 states— Relation of yield of hay to 
effective rainfall —Tillage methods only partly appli- 
cable to small grains 227 128 

Tillage to Save Moisture is Chiefly Effective in Saving Winter 
and Early Spring Bains.— hate rains largely absorbed 
by the surface three inches — Roots develop close to 
the surface in late summer 128 129 

Midsummer and Early Fall Crops Difficult to Baise without 
Irrigation.— Summer vains less effective— Yields of sec- 
ond crop clover— A crop of barley and hay the same 
season -j 9q_-i q-i 



Contents xi 

PAGES 

Fall Plowing to Co7iserve Moisture. — How most effective- 
Amount of moisture saved— Most important in sub- 
humid climates— Applicable to orchards and small 
fruits 131-133 

Subsoiling to Conserve Moisture. — Magnitude of the effects 

— Duration of the effects 133-138 

Explanation of Effects of Subsoilifig .—InQveases^ v^^ater ca- 
pacity of soil stirred— Decreases the capillary conduct- 
ing power— Allows the water to enter soil more deeply 
— Larger per cent of water available to crops 139-142 

Earth Mulches. — Conditions modifying effectiveness— Loses 
in effectiveness with age— Other mulches— Too close 
pasturing wasteful— Value of surface dressings of ma- 
nure—Harrowing and rolling small grains after they 
are up 142-147 

Early Tillage to Save Moisture .—Amount saved— Most 
effective tools — Early stirring rather than early 
planting 147-151 

Danger of Plowing Under Green Manures. — Catch crops in 

humid and sub-humid climates 151-153 

Summer Fallowing in Relation to Soil Moisture 153,154 

Influence of Summer Falloiving on Soil Moisture and on 

Plant-food 154-157 

Old Systems of Inter tillage.— J ethro Tull's method — 
Hunter's modification — The Lois-Weedon system — 
Planting and tillage to utilize the whole rainfall — 
Distance roots of corn and potatoes spread laterally— 
Distribution of moisture in potato field— Lateral feed- 
ing of oats— Horse -hoeing grain a form of summer 

. fallowing 157-163 

Frequency of Tillage to Conserve Soil Moisture.— Should 
often take place at the earliest possible moment— Dan- 
ger from late tillage 164, 165 



xii Contents 

PAGES 

Tlie Proper Depth of Surface Tillage and Bidged and Flat 
Cultivation. — Depth of early tillage — Deep ridges objec- 
tionable — Ridge cultivation may be advisable for potato 
culture 165,166 

Boiling in Belation to Soil Moisture. ^Firming the surface 
to establish capillary connection with the soil below — 
Rolling may warm soil — Rolling may bring water to the 
surface — The press drill 166,167 

Destructive Effects of Winds. — Conditions for injury — De- 
structive effects on sandy lands — Influence of groves 
and hedgerows on evaporation — Protective influence of 
grass — The value of hedges in windy sections 168-170 

CHAPTER IV 

The Increase of Yield Due to Irrigation in Humid Climates 

(pages 171-195) 

Dnportance of the Amount and Distribution of Water in 
Potato Culture, and the Advantage of Irrigation in Cli- 
mates like Wisconsin. — T\xn.Q and method of planting — 
Amount of water used — Differences in yield 171-175 

Effect of Supplementing the BainfaU in Wisconsin for Cab- 
bage Culture. — Method of planting — Weight of heads — 
Influence on yield of thick and thin planting — Amount 
of water given crop 175, 176 

Effect of Supplementing the BainfaU ivith D'rigation on the 

Yield of Corn. — Difference in yield and in water used. . 176-178 

Effect of Supplementing the BainfaU with Irrigation on the 

Yield of Clover and Hay 178, 179 

A Crop of Barley and a Crop of May the Same Season 179-181 

Effect of Supplementing the BainfaU for Strawberries 181 



Contents xin 

PAGES 

Closer Planting Made Possible hy Irrigation— Breathmg 
room in the soil limited— Soil temperature lowered by 
close planting —Amount of sunshine limited — Ten- 
dency to lodge when planted too close— Possible insuf- 
ficiency of carbon dioxide— Amount of carbon used by 
maize 181-187 

T]ie Maximum Limit of Productiveness for ilfai^e.— Mean 
weio-lit of plants— Maximum yields computed— Observed 
yields 187-190 

Observed Yields of Maize i^er acre, Planted in Different 
Degrees of Thickness and with Different Amounts of 
^^^e^,_Yields of dry matter -Yields of shelled corn. . 190-193 

Influence of Thick Seeding and Irrigation on the Develop- 
ment of the P/awf.— Lengthening of the nodes 193-195 



CHAPTER V 

Amount and Measurement of Water for Irrigation 
(pages 196-221) 

The Maximum Duty of Water in Crop Production 196-199 

Conditions which Modify the Amount of Water Required for 
Irri^a^iori. —Peculiarities of crop— Character of soil- 
Character of subsoil— Character of rainfall— Frequency 
and thoroughness of cultivation— Closeness of planting 
—Fertility of land- Frequency of applying water 199-208 

Amount of Water Used in Irrigation.— In Italy— In Spain 
and France— In Egypt— General tables— Mean amount 
— For sugar cane — Highest probable duty, table 
Bushels of grain per cubic foot of water, table 208-217 

Duty of Water in Bice Culture 217,218 

Duty of Water on Water-meadows 219,220 

'Duty of Water in Cranberry Culture 220,221 



xiv Contents 

CHAPTER VI 

Frequency, Amount and Measurement of Water for Single 
Irrigations (page 222-247) 

PAGES 

Amount of Water for Single Irrigations. — Soil leaching in 
humid climates — Conditions which determine the 
amount of water used — Conditions which determine the 
frequency of irrigation . . 222-224 

Capacity of Soils to Store Water under Field Conditions. — 
Amount of soil moisture when growth was cheeked — 
Upper and lower limits of best amount — Amount 
needed for one irrigation 224-227 

Depth of Boot Penetration. — Prune on Peach — Apple — 

Grape — Raspberry — Strawberry — Alfalfa 227-234 

Frequency of Jn-igrai^ow.— Theoretical — For wheat — For 
maize — For clover, alfalfa and meadows — For potatoes 
—For rice 234-239 

Measurement of Water. — Necessity — Advantages 239 

Units of Measurement. — Acre-inch — Acre-foot — Second- 
foot— Miner's inch 239-241 

Methods of Measurement. — Time division — Subdivision of 

laterals — Use of divisors — Use of modules 241-247 



CHAPTER VII 

Character of Water for Irrigation (pages 248-268) 

Temperature of Water for Irrigation. — Best temperature — 
Danger from cold water — Amount soil temperature may 
be lowered 248-251 

Fertilizing Value of Irrigation Water. — Amount in two acre - 

feet 251-253 

Sewage Water for Irrigation. — On Craigentinny meadows — 

Healthfulness of milk from sewage grass 253-258 



Contents xv 

PAGES 

The Value of Turbid Water in Irrigation.— Uio Grande— 

Po— Nile— Durance 259, 260 

Improvement of Land % S:ilting .—Wsbr^ting or colmatage— 

Silting of gravelly soils 261-264 

Opportunities for Silting in Eastern United States. — In Wis- 
consin and Michigan— In New York and New Jersey— 
In the South 264-266 

Alkali Waters not Suitable for Irrigation.— Safe and unsafe 

alkali waters 266-268 

CHAPTER VIII 

Alkali Lands (pages 269-289) 

Characteristics of Alkali Lands 269, 270 

Causes of Injuries by Alkalies .—F\a&mo\yi\Q effects— Toxic 

effects 270, 271 

How Alkalies Accumulate in the Soil.— By capillarity— In 

marsh soils by underflow 272-274 

Intensive Farming may Tend to the Accu7nulation of Alkalies. 274, 275 

Amount of Soluble Salts which are Injurious in ^o^7s.— Con- 
clusions of Plagniol— Of Deherain— Of Gasparin— Of 
Hilgard— Plasmolytic action 275-278 

Composition of Alkali Salts.— In California— In Washington . 278-280 

Appearance of Vegetation on Alkali Lands.— In arid regions— 

In humid regions • 281-283 

Conditions which Modify the Distribution of Alkalies in Soil. 

—Tillage— Shading— Action of roots 283, 284 

Use of Land Plaster to Destroy Black Alkali.— B.i\garQVs 

conclusions 284, 285 

Kinds of Soil ivMch Soonest Develop Alkali 286 

Correction of Alkali Water before Use in Irrigation 287 

Drainage Must be Ultimate Remedy for Alkali Lands 287-289 



xvi Contents 

CHAPTER IX 

Supplying Water for Irrigation (pages 290-328) 

PAGES 

Diverting Biver Waters. — Sirhind canal — Kern Island canal — 
Dangers from seepage — Eedlands system — Redwood 
pipe line — Inverted siphon — Redwood flume — Cement 
flume — Cement hydrants 290-304 

Diverting Underground Waters. — By submerged dams — By 

submerged canals— By tunnels 304, 305 

Diverting Water by Tidal Damming 306 

Diverting Water hij Power of the Stream. — Undershot wheels 
— Bucket wheels — Turbines — Hydraulic rams — Ram- 
ming engines— Siphon elevator 306-310 

Utilizing Storm Waters for Irrigatioyi 311, 312 

Wind Power for Irrigation. — Record of experiments 312-316 

Water Pumped in 10- day Periods. — Number of acres a 

windmill may irrigate 316-318 

Necessary Conditions for the Highest Service with a Wind- 
mill. — Good exposure — More than one pump — Storage 
system 318, 319 

The Use of Reservoirs. — Construction — Size to supply given 

areas 320-323 

Pumping Water with Engines. — Cost with gasolene — With 

steam— In Egypt 324 327 

Use of Animal Power for Lifting Water for Irrigation. — 

Persian wheel — Bucket pump— Doon- Shadoof 328 

CHAPTER X 

Methods of Applying Water in Irrigation (pages 329-402) 

Principles Governing the Wetting of Soils. — Influence of 

texture — Effect of soil becoming dry 330-334 



\ 



Contents xvii 

PAGES 

Principles Governing the Puddling of Soils. — Character of 

puddling — Bad effects — Precautions to prevent 334-33G 

Principles Governing the Washing of Soils. — The common 
mistake — What constitutes good irrigation — Methods 
which prevent washing 337^ 338 

Field Irrigation by Flooding. — Two different types — Used 
most where intertillage cannot be practiced — Flooding 
by running water — As practiced in Colorado — Where 
slopes are steep — Where fields are short — Flooding by 
cheeks — Size of checks — Forming checks — On irregular 
slopes — Handling the water — Large systems -Forming 
check ridges 338-350 

Fitting the Surface for Irrigation. — Leveling devices — 

Shuart land grader — French land grader 351, 352 

Field Irrigation hy Furroivs. — Adapted to intertillage crops 
— Watering before planting — Irrigation of potatoes — 
Watering alternate rows — Lateral spreading of water — 
Effect on yield —Watering sugar beets and maize 352-359 

Water-meadows. — Laid out for continuous flow — System at 
Salisbury, England — In Italy — In Belgium — Mountain 
meadows 359-365 

Irrigation of Cranberries. — Laying out the marshes — Rapid 
flooding and draining — Irrigation of small fields by 
pumping 365-368 

Irrigation of Bice Fields. — South Carolina system — Trunks 
— Germinating the rice — Dry hoeing — Irrigation after 
dry growth stage — Prevention of red rice — Upland irri- 
gation 368-373 

Orchard Irrigation. — Furrow method best — Capillary 
spreading of water — Distributing flumes — Foot ditch — 
Watering by ring furrows 373-381 

Cultivation after Irrigation. — The cardinal principle — 
Forms of orchard cultivators — Importance of cultiva- 
tion in humid climates. 381-383 



xviii Contents 

PAGES 

Small Fruit Irrigation. — Frequent irrigation needed for 
strawberries — Watering alternate rows to facilitate 
picking 383, 384 

Garden Irrigation. — Bed irrigation — Bailing system — Ridge 
and furrowmethod— Basin flooding —At Gennevilliers— 
At San Bernardino 384-391 

Irrigation of Lawns and Parks. —Inadequacy of spraying — 

Rainfall of humid climates not usually sufficient 391-396 

iSub- irrigation. — Not economical of water — Water not ap- 
plied where most effective — Unequal wetting of the 
soil— First cost heavy — May be applicable in certain 
cases 396-402 

CHAPTER XI 

Sewage Irrigation (pages 403-414) 

Objects Sought in Sewage Irrigation.— Destruction of or- 
ganic products — Utilization of fertility carried 403 

Climatic Conditions Favorable to Sewage Irrigation. — Warm 
climates best suited — Cold soils chiefly filters — Large 
area required for winter handling 404, 405 

Process of Seivage Purif cation by Irrigation and Intermit- 
tent Filtration. — Essential conditions — Effect of too 
rapid application 405, 406 

Soils Best Suited to Seivage Irrigation. — Lighter loams and 

sandy soils— Any soil adapted if area is sufficient 406 

Desirability of Wider Agricultural Use of Sewage in Irriga- 
tion.— Kxsuniples of valuable results — Sections of country 
specially adapted to it 406-409 

Crops Suited to Seivage Irrigation. — Grass, most generally 
— Soil for intertillage crops fertilized by winter irriga- 
tion—Potatoes at Croyden — May injure grass if applied 
in winter 409-413 

Influence of Sewage Upon the Health.— Xt Gennevilliers — 

Purity of eflfiuent compared with well water 413, 414 



Contents xix 

Part II 
FARM DRAINAGE 

CHAPTER XII 
Principles of Drainage (pages 415-466) 

PAGES 

TJie Necessity for Drainage. — Removal of injurious salts — 

Better soil ventilation — Makes the soil more firm 416, 417 

The Demands for Air in the Soil.- Supply of free oxygen — 

To lessen denitrifieation— Facilitates chemical changes. . 418, 419 

How Drainage Ventilates the Soil. — Permits roots and bur- 
rowing animals to go deeper — Develops shrinkage 
checks — Favors granulation of soil — Barometric and 
temperature changes — Suctional effect of rains 419-421 

Too Thorough Aeration of the Soil. — Leads to destruction of 

humus — Care of open soils 421,422 

Drainage Increases the Supply of Available Moisture for 
Crops. — Deeper root penetration — Stronger capillarity 
— Stronger nitrification — Deeper ground water more 
available 422, 423 

Soil Made Warmer by Drainage. — By lessening surface 
evaporation — By lowering specific heat — Observed 
differences of temperature 423-425 

Importance of Soil Warmth. — Relation to germination — 

Hastens development of plant -food 425-428 

Conditions under which Land Drainage Becomes Desirable. — 
Lands subject to frequent overflow — Lands with strong 
underflow near surface — Tidal plains — Flat lands with 
heavy subsoils 428 

Origin of Ground Water and its Relation to the Surface. — 
Vertical movement of rains — Surface of ground water 

Lines of flow — Growth of rivers 429-435 



XX Contents 

PAGES 

Bate at ivMch Ground Water Surface Rises away from the 
Drainage Outlet. — In tile-drained field — Where not 
tile-drained 435, 436 

Depth at wliicli Drains should he Placed. — Kind of crop — 
Seasonal changes of ground water — Character of soil — ■ 
Distance between drains 436, 437 

Distance Between Drains. — Texture of subsoil — Depth of 
drain — Interval of time between rains or irrigations — 
Climatic conditions 437, 442 

Kinds of Drains. — Closed — Open — Stone — Wood — Brick 

—Peat— Tile — Cement 443-445 

Hoiv Water Enters Drains. — Rate through the walls — 
Through the joints — Care in making close joints — Use 
of collars 445, 446 i 

Fall or Gradient of Drains. — Highest practicable — Selecting 

course for the main — Care in laying to grade — Change I 

of grade — Use of silt well 447-449 

Size of Tile. — No specific statement possible except where 
all details are known — Size increases with length — 
Seldom smaller than three inches in diameter — Example 
of sizes and lengths 449-452 

Outlet o/ Dmins.— Should have a clear fall — Precautions 
against injury from frost — Connecting laterals with 
mains. . 453, 454 

Obstructions to Drains. — From roots— Kinds of trees most 

troublesome 455, 456 

Laying Out Systems of Tile 456-459 

Intercepting the Underflow from Hillsides 459, 460 

Draining Sinks and Ponds. — By intercepting surface drain- 
age — By subdrainage 460-462 

TTie Use of Trees in Drainage 4'-2, 463 



r 

Contents xxi 

PAGES 

The Use of the Windmill in Drainage. — Arrangement for 

winter pumping — Subirrigation as an adjunct 463, 464 

Lands which must he Surface Drained. — Ancient lake bot- 
toms underlaid with clay — Sections where there are no 
natural surface outlets 464-466 



CHAPTER XIII 

Practical Details of Underdraining (pages 467-492) 

Methods of Determining Levels. — Kinds of levels 469-471 

Leveling a Field. — Making contour map — Using the level. . 471-473 

Location of Mains and Laterals. — Securing the greatest 

fall 474-476 

Staking Out Drains. — Grade pegs 476, 477 

Deternmiing the Grade and Depth of Ditches. — Method of 

marking stakes for use of ditchers 477-481 

More than One Grade on the Same Drain 481 

Digging the Ditch. — Tools used — Method of procedure — 

Methods of filling 481-488 

Cost of Underdraining . — For mains — For laterals 489-491 

Peat Marshes 491, 492 



IRRIGATION AND DRAINAGE 



INTRODUCTION 

GENERAL REMARKS ON THE IMPORTANCE OF WATER 

The watering of laud, which is irrigation, and the 
withdrawal of such part of that water as does not 
evaporate, which is land drainage, are two methods, 
one the opposite of the other ; but, looked at in the 
broadest sense, both are natural, and each is as old 
as the time when the rains descended upon the first 
lands which rose above the ocean's level. The periodic 
watering and draining of the earliest rock fragments 
which covered the earliest lands, and which came to 
be the earliest soils, constituted at once the most 
primitive, the most profound, and the most persis- 
tent environment to which all forms of land -life 
have been forced to adapt themselves. 

Since the very earliest forms of life probably came 
into being in the water, and were composed in large 
measure of it, it is not strange that we yet know of 
no forms which can live without water, and to which, 
indeed, water is not the most fundamentally important 
substance and food. It is so, not more because it 
makes up so large a part by weight of all living and 

A (1) 



2 , Irrigation and Drainage 

growing parts of plant life, than because it is the 
medium in which the transformation of the crude 
materials into assimilable food -products takes place, 
and through and by means of which these products 
are transported to their destinations at the various 
points of growth. It is only when we fully appreciate 
the important role played by water in crop production, 
that we are in position to see how necessary to large 
yields is the right amount of water at the right time, 
and thus be led to insure to our crops a sufficient 
irrigation and an adequate drainage. 

Since the falling of rain upon soils has always 
been intermittent in its character, and during the in- 
tervals of fair weather a part of the water so given . 
to the soil has been lost by drainage, land vegetation, 
during its evolutionary stages, has become fitted to do 
its best work when the soil is watered once in about 
so often, and when that soil retains a certain amount 
of the rain which falls. But the intervals between j 
rains in almost all countries are irregular in length, . 
and the amount of rain which falls at one time also 
varies between very wide limits, so that in many if 
not in the majority of climates, those seasons are rare _| 
indeed when a crop can be carried to maturity with 
the soil containing at all times the best amount of 
moisture. This being true, there will occur times with 
almost all soils when they would give larger yields if 
they could be artificially irrigated or artificially drained, 
according as the period is one of deficient or of exces- 
sive rain. 

But not all soils are alike in their capacity for re- 



Soil Texture in Relation to Rainfall 3 

taining moisture and of permitting it to drain away, 
and this being true, under one and the same conditions 
of rainfall one field might be benefited by irrigation 
while another one would profit by better drainage. 

It is this fact of varying capacity of soils to store 
water for given periods of time that, in the long strug- 
gle for existence and of fitting and refitting among 
plants, has led to the evolution of certain species 
which can thrive best in a soil of coarse texture, re- 
taining but sinall amounts of water for anj' length of 
time, while other species have become adapted to the 
soils of finer texture and higher water capacity. This 
is a fact of fundamental importance, not only in decid- 
ing what crops may be grown in a given soil, but 
whether or not it will be desirable to irrigate such 
lands beyond the natural rainfall. 

A soil of fine texture is spoken of as the best grass 
land, for example ; but this has reference, in a very 
large degree, to a certain amount and frequency of 
rainfall, which chances to be such as to maintain for 
the grasses the amount of water in the soil under 
which they have become accustomed to grow best. If 
there were another soil in the same locality, of similar 
composition but of coarser texture, and so of smaller 
water capacity, it is most probable that this soil would 
be converted into equally good grass land, giving just 
as large or even larger yields per acre, if o\\\j the 
natural rainfall were supplemented by artificial irri- 
gation, so as to hold the water of the soil up to that 
quantity which the grass has become accustomed, by 
long breeding, to use. 



4 Irrigation mid Drainage 

Then, again, on the other hand, the soil which for 
a given climate is so close-grained that it does not 
drain sufficiently between rains to leave it dry enough 
for those crops which have become accustomed to the 
smaller water capacity of the coarser soils, may be all 
right for the dry -soil crop, provided it occurs in a 
locality of smaller or less frequent rainfall. Or, again, 
in the region of heavier rainfall, this soil may be fitted 
for the dry-soil crop by thorough under-draining, when 
the lines of tile are placed close enough to draw down 
the water to a sufficiently low point to leave the soil 
with the amount of moisture which is suited to the 
crop in question. 

Another soil may be very deep and exceptionally 
well aerated, on account of its peculiar texture, so 
that the roots of cultivated crops easily penetrate it to 
much greater depths than is possible in the closer, 
more compact, non- aerated subsoils of other localities. 
When this is the case, as appears often to be true 
in arid and semi- arid climates, notably in parts of 
the San Joaquin Valley, in California, the smaller rain- 
fall of the winter season penetrates the soil so deeply, 
and returns to the surface by capillarity so slowly, that 
fair and even large crops are often raised on these 
soils without artificial irrigation, yet not a drop of 
rain may fall upon the land from May first to Septem- 
ber. So different are the conditions in humid soils, like 
those of the eastern United States, that even a period 
of ten days without rain, especially if it occurs in the 
height of the growing season, is sure to bring marked 
distress even to field crops like maize. 



Apparently High Service of Water 5 

One of the most striking features of the arid sec- 
tions of the United States, which attracted the writer's 
attention during his travels through the West, was this 
apparently greater service of water in crop production 
than is realized in the more humid climate of the east- 
ern section of this country. Reasoning from general 
principles, one is naturally led to anticipate that in an 
exceptionally dry atmosphere and under a clear sky, 
such as we have in the western United States, the rate 
of evaporation, both from soil and vegetation, would 
be exceptionally rapid, and hence that enormous quan- 
tities of water would be required in crop production, 
when compared with the demands of crops under more 
humid conditions. 

Such, however, does not appear to be the case, and 
it is this fortunate relation which makes it possible 
for larger areas to be placed under irrigation with the 
limited amounts of water than would be possible were 
the conditions of the soil more like those of humid 
climates. 

It is not easy to assign a thoroughly satisfactory 
set of reasons for this marked difference without a 
more detailed study of the field conditions than has 
yet been made. It seems quite probable, however, that 
prominent among the reasons to be assigned for these 
differences is the one to which reference has already 
been made : namely, the texture of the soil, which 
allows the water to distribute itself evenly and rela- 
tively deep in the soil, and it does not return 
readily and rapidly by capillarity to the surface to be 
lost. 



6 Irrigation and Drainage 

In passing south from San Francisco, through Lath- 
rop, Merced and Fresno, to Bakersfield, in California, 
we pass across a long stretch of country where there 
is at present relatively very little irrigation, and yet 
through all of the country north of Merced wheat has 
been extensively grown, and during the early years, 
when the soil was new, large yields per acre have been 
realized without irrigation, the crop depending upon 
the rain which falls during the rainy season of winter 
and sinks into the soil, to be later used by the deeper 
feeding roots. In discussing the matter with Professor 
Hilgard, he informed me that the roots of crops 
penetrate these soils much more deeply than is normal 
to them under other conditions, and that some plants, 
when brought here, really change their habits of root 
growth through a dying off of the normal surface 
feeders on account of an insufficiency of moisture in 
the upper layers. 

Professor Hilgard further informed me that over 
much of the state of California the rains only wet 
down a relatively short distance, and that beneath this 
zone of moistened soil the balance is often almost 
air- dry, extending, in certain cases which have come 
under his observation, to depths as great as forty feet. 
Where such conditions as these exist there is, of 
course, no possibility of crops deriving a supply of 
moisture through natural sub -irrigation from waters 
from the foothills or higher mountain masses which 
rise above the plains. 

My own observations on the soils of humid cli- 
mates convince me that the zone of dry soil to which 



Apparently High Service of Water 7 

reference has been made must act as a powerful ad- 
junct in the retardation of both capillary and gravi- 
tational movements of water below the reach of deep 
root feeding ; and if this is true, practically all loss of 
water by downward percolation is prevented, and the 
whole rainfall not lost by surface evaporation becomes 
available for crop production. 

There is another condition, brought about by the 
presence of the layer of air - dry soil beneath the 
moisture -bearing zone, which in humid regions only 
exists in exceptional localities, and which may have an 
important influence in making a larger part of each 
year's rainfall available for crop production. I refer 
to the possibility of the large amount of air stored in 
the air -dry soil beneath the moist layer contributing 
to deep soil breathing. By slow diffusion upward, and 
by movements induced by changes in atmospheric pres- 
sure, the roots may be supplied with oxygen from be- 
low as well as from above, and thus have their feed- 
ing depth lowered on this account beyond what is 
usual in humid soils. So, too, it appears to be quite 
possible that nitrification and other biologic processes 
may be permitted to go forward under these condi- 
tions, when in humid soils they are largely prohibited 
for lack of sufficient aeration. 

These suggestions, however, do not appear to offer 
an adequate explanation of the ability of crops to 
reach maturity in the arid soils of the West without 
irrigation, when there is no rain for such long inter- 
vals ; for, as we approached Merced from the north, a 
very sandy belt of land was passed which was white 



8 Irrigation and Drainage 

and glistening in the snn, and which drifted as badly 
as much of apparent!}' similar land in Wisconsin, and 
yet on these coarse sands wheat was being harvested 
which would give larger yields than would be expected 
on such lands in Wisconsin with a summer rainfall 
of not less than ten inches. But here the crop had 
stood and matured from early May until the end of 
July without irrigation and without rain. One is led 
to question whether it ma}^ not be true that, under 
the stress of such arid conditions of both atmosphere 
and soil, plants of some kinds may develop a texture 
of a closer nature, with fewer and smaller breathing 
pores, and thus reduce the loss of moisture through 
their surfaces much below what is normal to the same 
species under more humid conditions of soil and atmos- 
phere. Such a question could, of course, readily be 
settled by a proper comparative study of tissues de- 
veloped under the two conditions ; but, so far as we 
know, it has not yet been done. It should be said, 
however, in this connection, that the seemingly greater 
service of water to which reference is here made may 
be more apparent than real. The climate of the region 
being warm, and wheat being sown from the begin- 
ning of the rainy season in November until the end 
of January, there is much time for the crop to germi- 
nate, and to get its root system thoroughly established 
in the ground, and to have made a very considerable 
growth, before the close of the rainy season earlj' in 
May. There are left, then, only the months of May 
and June during which the crop must complete its 
growth without rain. It is true that this is a long 



Advantages of Abundant Moisture 9 

period, and in humid climates, where the growth of 
vegetation can only heg'ui in March or April, even 
though the rainfall were the same as in the San Joaquin 
Valley, crops like wheat could not be matured ; and it 
is quite possible that this would also be true of the 
country in question did it have an ice-bound winter. 

In the vicinity of Fresno, California, where a large 
acreage of raisin grapes are grown on a sandy loam, 
generally without irrigation, it is the belief of many 
of the growers that their vinej-ards derive not a little 
moisture through a seepage from the canals and ditches 
of the district, whose waters are more generally used 
in the irrigation of alfalfa ; but, as many of these 
vineyards are considerable distances from both canals 
and ditches, it is, perhaps, more probable that the 
grapes survive through extremely deep and wide root- 
feeding and, perhaps, small foliage evaporation. It is 
the naturally small water capacity of the Fresno soils, 
and those referred to near Merced, which makes it so 
difficult to understand how, even with very wide and 
deep root -feeding, moisture enough could be gathered 
to maintain growth and carrj^ a crop to maturity 
without rain during the summer season, and without 
irrigation . 



ADVANTAGES OF AN ABUNDANT SUPPLY OF 
SOIL MOISTURE 

While there are such cases as those cited above, 
in which plants appear to thrive and to produce fair 
yields with relatively small amounts of water, yet it 



10 Irrigation and Drainage 

is a matter of universal experience in humid climates 
that on claj'ey soils heavy protracted spring rains con- 
tribute more to the production of large crops of grass 
than all the manure which farmers can put upon their 
lands, and that with dry springs fertilizers, of what- 
ever sort and however applied, are of but little avail. 
So, too, four weeks of copious, timely, warm rains fall- 
ing upon fields of potatoes after the tubers begin to 
set, and of corn after the tassels and silk begin to 
form, are certain to be followed by enormous yields, 
even when the soil is not rich, unless frost or disease 
intervenes. On the other hand, let the tuber and grain- 
forming period of these crops be one of drought, and 
it is only those soils which are most retentive of mois- 
ture, and which have been most skillfully handled, that 
are able to mature even moderate yields, though the 
land be very rich. 

What, then, do warm spring and summer rains and 
warm, sweet irrigation waters do in the soil which con- 
tributes so much to plant growth ^ In the first place, 
it is only through the soil, where very extensive absorb- 
ing surfaces of root hairs are developed, that plants 
are able to obtain the very large amounts of water 
they need for food and for the maintenance and carry- 
ing forward of the physiological processes which are 
associated with plant growth. 

But it is not alone for the crop which is being grown 
upon the ground that water is needed in the soil ; for 
it must never be forgotten that there are living within 
the dark recesses of the soil organisms of various kinds 
upon whose normal and vigorous activity depends, in 



Advantages of Ahtmdant Moisture 11 

a high degree, the magnitude of the specific crop which 
is to be harvested. The germs which react upon the 
dead organic matter in the soil, converting it into 
ammonia, the germs which change the ammonia into 
nitrous acid, and the germs which transform the nitrous 
acid into nitric acid, — which is the real nitrogen supply 
of most of the higher plants, — each and all are depend- 
ent for their proper activity upon the right amount of 
moisture in the soil. Then, there are those symbiotic 
forms of lowly organisms whose great mission it is 
to take the free nitrogen from the air and compound 
it into such forms as shall leave it available for the 
higher plants, and which ^ like all other forms of life, 
must have water and to spare if they are to perform 
their work. Let the water content of any soil be 
reduced below a certain amount, and all of these vital 
processes are inevitably slowed down ; let it be reduced 
to a still lower degree, and the whole line is at a com- 
plete standstill. 

Now, in humid regions, where the subsoils are much 
of the time water-logged, and where, as a consequence 
of this, there is but little soil ventilation, the plant- 
food builders to which reference has just been made 
are all of them forced into a thin zone close to the 
surface of the ground, where their work must all be 
done ; but if this surface zone is allowed to become 
dry, then the nitrogen -supplying processes must come 
to a standstill, and the crop which is growing above 
the ground must have its growth checked, even though 
it has put its roots down into the subsoil where mois- 
ture for its own purposes may be had. Indeed, we may 



12 Irrigation and Drainage 

well believe that one of the chief causes which has led 
the higher plants to send their roots foraging so deeplj^ 
into the ground is this great need of water in the sur- 
face layer, where the nitrogen suppliers dwell, and for 
the express purpose of not drawing upon this supply 
too extensively, and thus leaving the surface soil to, 
become too dry. It is true that when heavy rains, 
come, or when irrigation waters are applied which lead: 
to the percolation of water downward, the nitrates 
which have been formed at and near the surface are 
dissolved and more or less completel}^ washed more 
deeply into the ground, where the deep -running roots 
are in position to take advantage of them and prevent' 
their being lost ; and thus a double gain is secured. 

Let us call attention to another important principle. ' 
In the soils which have been highly manured, or which 
are naturally w^ell supplied with organic matter ready 
for decay, large amounts of nitrates are rapidly formed. 
Under such conditions the moisture wiiich invests the 
soil grains rapidly approaches saturation, and finally 
reaches a point when it is carrying so many salts in 
solution that the water is no longer suitable for th^ 
use of the germs which have given rise to the salts, 
and their activities are on this account brought to a 
standstill. But let a rain come which produces perco- 
lation, or let the field be irrigated sufiiciently to pro- 
duce the same effect, and at once the salts which have 
been inhibiting the nitrate -forming process are washed 
out and a fresh supply of water is left, which at once 
becomes a stimulus for increased activity, while the 
ready -formed salts containing nitric acid are carried 

1 



Fertility Influenced by Drainage 13 

to a lower level, where they may be taken up by the 
i deeper -feeding" roots. Here, then, we are led to see 

yone of the ways in which water, applied at the sur- 
face at opportune times, acts as a wonderful stimulus 

., to plant growth. 

If, now, we turn from the irrigation to the drain- 

^ age side of the same problem , we shall see in another 
way how fundamentally important this principle is. 

, Let a soil be inadequately drained, and the roots of 

. the plants will be forced to occupy the surface soil, 
for they cannot abide in the water -logged region. 

.Then, if heavy rains come and percolation results, all 

jof the unused nitrates which may have been in the 
soil at the time are at once washed below the roots, 

tand perhaps entirely lost to the crop. But, on the 

I other hand, if the soil had been properly drained, so 
ithat the roots of the crop could have been two, three 
or four feet below the surface, then, as has been pointed 

,out, the nitrates would have been washed to the roots, 
where they would have become at once available. 
Then, too, when a dry period comes, with all the life 
•processes going on in the soil confined close to the 
surface, the great demand for water from the roots 
forces them at once to so completely dry out the sec- 
tion they occupy that a violent check is at once put 
both upon the plant itself and upon all the food-form- 
ing processes in the soil ; for, under these conditions, 
it is usually impossible for capillarity to keep pace 
\with the loss of water from above, and the soil quickly 
becomes too dry. 

So far we have been speaking of the importance of 



14 Irrigation and Drainage 

water in the soil to the direct vital processes which 
are going on there whenever steady growth is taking 
place. But there are other processes which are purely 
physical, to which attention needs to be called before 
we have brought into view the full line of operations 
to which this great agent, water, leads. 

Other plant-foods, — those which contain the phos- 
phoric acid, potash, lime, magnesia, iron and sulfur, — 
must be taken from the inert solid form in the soil 
into solution in water before they can be of any service 
in plant growth, and this is another of the important 
roles which water has to play in the life processes of 
the soil. Then, too, all water used in irrigation, and 
even rain water, contains^ larger or smaller quantities 
of plant -food, either directly in solution or borne in 
suspension, which adds so much to the fertility of the 
soil itself. 

So, too, all waters which have been exposed to the 
atmosphere have become charged with oxygen, carbonic 
acid and nitrogen, which they carry with them into 
the soil, and these always aid, in one way or another, 
both the physical and the life processes which make 
for fertility of the land. And, again, when a large 
volume of warm water falls upon or is applied to the 
soil, and it sinks deeplj' into it, it carries with it not 
only its own warmth, but also the heat which it may; 
have absorbed from the surface of the ground; and; 
this warmth, carried deeply into the ground, makes 
the root action stronger and at the same time increases 
the rate of solution of plant -food from the soil grains. 
When we have made this brief survey of what warm 



Water only One of the Necessary Plant -foods 15 

rains and sweet irrigation waters do in the soil, we 
may not be surprised to see the large yields of grass 
or of potatoes or corn it is capable of helping the 
soil and the sunshine to bring forth as the product 
of a summer's work. 

WATER ONLY ONE OF THE NECESSARY PLANT -FOODS 

In view of the facts which have just been pre- 
sented, it is not at all strange that the ancient Egyp- 
tian and Grecian philosophers, with their lack of exact 
knowledge and under their arid climatic conditions, 
should have come to believe that water is the sole 
food of plants ; nor that this opinion should have 
been held until nearly the beginning of the eighteenth 
century. As a matter of fact, water does contribute 
more than half of the materials which make up the 
dry matter of plants, and, as water, it constitutes from 
three -fourths to more than nine -tenths of their green 
weight. 

But while these are the facts, and while it is true 
that abundant and timely rains do make compara- 
tively poor soils produce large yields, it must not be 
inferred that, with ample and timely supplies of water 
applied to the soil, all else may be neglected and the 
hope entertained that any agricultural soil will thus 
be held up to a high state of productiveness for an 
indefinite term of years. 

It is a matter of universal experience that sewage 
waters, not contaminated with poisonous compounds 
and not too highly concentrated, cause lands to give 



16 Irrigatioyi and Drainage 

much larger returns in grass than do river, lake or 
well waters. The writer learned, while visiting the 
celebrated Craigentinny meadows near Edinburgh, that 
the purchasers of the grass from those lands are very 
particular to specify, as a condition of their purchase, 
that their grass shall be watered with the day sewage, 
which contains a higher per cent of soluble and sus- 
pended organic matter than that of the night ; and 
they are also particular to stipulate that they shall 
have the first rather than the second or third use of 
the water, knowing that water which has passed over 
a cultivated field or meadow has lost something of its 
fertilizing value. 

It is asserted, also, by the owners and renters of 
water meadows in the south of England, where the 
irrigation is directly from the streams, that that land 
which receives the water first is most benefited by it. 
It is true that there are those who contend that on their 
lands the second and third waters are as good as the 
first, but this is quite likely to be due to the presence 
in those particular soils of an abundance of the sub- 
stances carried by the waters. 

It is, however, impossible to overestimate the im- 
portance of water as a plant-food. It is indispensable 
and is used more than any other substance. It must 
be borne in mind, however, that irrigation waters are 
seldom, if ever, a complete plant-food. 



THE AMOUNT OF WATER USED BY PLANTS 



The amount of water which is required to mature crops of 
various kinds under field conditions varies between wide limits 



i 



I 



Amount of Water Used by Plants 17 

but just what are the precise factors, and what their quantitative 
relations, is not yet so definitely known as it needs to be. The 
problem is manifestly a complex one, and many of the factors 
are obscure, and will only be made known in their quantitative 
relations after much patient critical work has been done having 
for its prime object the solution of this problem. 

It has already been pointed out that there appears to be 
relatively less water consumed in the production of a pound of 
dry matter under some of the conditions which exist in arid 
America than is required in the more humid sections of this 
country, and that it appears probable that a part of this differ- 
ence is to be sought, possibly, in adaptive functions in the plant 
itself and a part in the differences of soil conditions. 

Under the natural conditions of the field, it would be expected 
that very much will depend upon the character of the season ; 
that is, whether the season is humid or dry, whether the tempera- 
tures are high or low, whether the wind velocities are strong or 
light, and whether the amount of sunshine is more or less. Very 
much, too, will depend upon the soil and the character of the 
rainfall, whether the soil is open and the rains are frequent and 
heavy, so that considerable amounts of water are lost to the crop 
by percolation and under-drainage, or whether the soil has a 
retentive texture, and the rainfall is so proportioned that rela- 
tively small amounts are lost, nearly all being used in the pro- 
duction of the crop. Then, too, the manner in which the crop is 
disposed on the field, whether it covers the surface closely, as do 
the grasses and small grains, or whether considerable areas of 
the field are exposed to the direct action of wind and sun, as in 
many of the hoed crops and in orchards, must have a marked 
influence in determining the actual amount of water which will 
disappear or will need to be applied during a season, in order 
t to maintain the best moisture conditions for the particular 
crop. 

Then, again, the treatment of the soil itself will have much 

' to do with the quantity of water which disappears at once from 

the surface without in any way benefiting the crop, and also the 

quantity which drops at once entirely through the root zone, con- 

B 



18 Irrigation and Drainage 

tributing nothing to the physiological processes which are involved 
in the production of the harvest sought. 

Irrigation and land drainage are, each of theua, nuethods of 
treatment of field conditions which aim to modify and control the 
quantitative relations of the water which the soil shall contain, 
and hence it becomes a matter of importance to know how much 
water is necessarily involved in the production of a given amount 
of a given crop. Much work has been done by various investi- 
gators bearing upon this problem, but in all of those eases the 
work has been by methods and appliances which have placed the 
plants experimented with under such conditions that the roots 
were forced to develop in a volume of soil which was much smaller 
than field conditions usually afford. In the writer's work, how- 
ever, he has aimed to give the plants more nearly the normal 
amount of root room ; and in one series has aimed, also, to so 
place the experiment that the plants should be growing as 
nearly as possibly under the meteorological conditions of the field 
crop. 

The apparatus used for this work is illustrated in Fig. 1, 
where, for the first trials, 50 -gallon vinegar casks were used for 
pots in which to place the soil. But after the first year's work 
these were abandoned, and there were substituted for them, for 
the field work, galvanized iron cylinders 18 inches in diameter and 
42 inches deep. These were placed in pits in the ground in the 
field, as illustrated in Fig. 1, so that the tops of the cylinders 
were at the level of the top of the field soil, and so that the cylin- 
ders in which the experimental plants were growing stood in the 
field surrounded by the crop of the same kind growing under field 
conditions. The object of placing the experiment in this manner 
was to secure for the plants, as nearly as possible, the meteorologi- 
cal conditions of the field, and these conditions were quite closely 
realized in all particulars except the one of soil temperature. In 
this particular the cylinders, being necessarily isolated from the 
body of the field soil in order that they might be weighed at any 
time, allowed the soil to take more nearly the temperature of the | 
atmosphere than was true of the deeper layers of soil in the field, 
and also to be subject to wider diurnal changes in the lower por- 



Water Eequired for a Pound of Dry Matter 19 




Fig. 1. Method used to measure the amount of watei* reqiiii-ed to produce 
a pound of dry matter. 

tions of the cylinders than could have occurred in the correspond- 
ing depths in the field soil. Just how these differences of tem- 
perature conditions have modified the results we are not yet in a 
position to say, but it is not likely that they have caused very 



20 Irrigation and Drainage 

wide departures from what would have been observed had it been 
possible to have measured as accurately the water consumed by 
the surrounding plants of the same kind which were growing at 
the same time in the field under every way normal field condi- 
tions. 

In all of these pot experiments, the effort has been to hold 
the amount of moisture in the soil at a constant quantity equal 
to that which was possessed by the field soil in the spring of 
the year, when it was in good working condition ; and this 
was done by weighing the cylinders periodically, usually as 
often as once a week, and then adding water in sufficient quan- 
tity to bring the weight of the cylinder back to the original 
amount. The cylinders were, of course, water-tight, so that the 
only loss was through evaporation from the surface of the soil in 
the cylinders and from the plants themselves. No effort has been 
made in these experiments to distinguish between the amount of 
water which actually passed through the plant and was -evaporated 
from its surface, and that which escaped from the surface of the 
soil in which the plants were growing, as to do this would 
necessitate the covering of the soil in which the plants were grow- 
ing so as to prevent evaporation from it. To do this effectively 
would interfere with the normal aeration of the soil, and thus viti- 
ate the results by producing abnormal conditions. During the 
work of the first year, when the wooden casks were used, there 
was probably some loss of water through the walls of the casks, 
due to capillarity in the wood and evaporation from it ; but 
the amount was probably small, because they were all well 
painted. 

The first year's trials were with oats, barley and corn. With 
the oats and barley the surface of the soil was not disturbed after 
seeding, but in the case of the corn the ground was stirred after 
each watering, so as to develop a soil mulch after the manner 
of field culture. In each case the work was done in dupli- 
cate. In the table which follows are given the results of these 
trials : 



Water Used by Plants 



21 



*Table shoiving the amount of water evaporated from plant and soil iji producing 
a pound of dry matter in Wisconsin in 1891 



Water used 

LBS. 

Barley 1 158.3 

Barley 2 141.03 

Oats 1 224.25 

Oats 2 220.7 

Corn 1 300.45 

Corn 2 298.65 



Dry matter Water per lb. of Water as inches 
produced dry matter of rain 



LBS. 


LBS. 


INCHES 


.3966 
.3488 


399 14 1 
404.33 J 


13.19 


.4405 


509.31 1 
493 63 J 


19.6 


.4471 


1.0152 
.9727 


295.95 ) 
307.03 i 


26.39 



It will be seen from an inspection of the table that the sev- 
eral experiments agree among themselves as closely as could be 
expected, and that the barley used 13,19 inches of water in 
coming to maturity, the oats 19.6 inches, and the corn 26.39 
inches. 

During the same season an effort was made to measure the 
water required for a crop of corn under perfectly normal field 
conditions. To do this two plots of ground, each 48 feet long 
and 42 feet wide, were planted to a local form of Pride of the 
North dent corn, in rows 3.5 feet apart and in hills 16 inches 
apart in the rows, the corn being thinned to two stalks in a hill 
after it had come up and was well established. At the time of 
planting, samples of soil were taken in 1-foot sections to a depth 
of 4 feet from six different places on each plot, and the water 
in the soil determined. This was also done when the corn was 
cut, in order to get a measure of the change in the water con- 
tent of the soil, which it was proposed to add to the measured 
rainfall of the growing season, to give the amount of water 
used. 

At the time of maturity, the whole of the corn of each plot 
was cut and dried in a large dry -house, in order to get an exact 
measure of the amount of dry matter produced. There is given 
below the water content of the soil in the two plots at the time 
of planting and at the time of harvest : 



*Eighth Annual Report Wisconsin Experiment Station, p. 126. 



22 Irrigation and Drainage 

*Table showing the changes in the water content of the soil upon ivhich com had 
been grown in 1890 under field conditions 

Dry weight of soil per First foot Second foot Third foot Fourth foot 

cubic foot 77.25 lbs. 79.79 lbs. 94.1.3 lbs. 98.07 lbs. 

PEROT. LBS. PEROT. LBS. PER CT. LBS. PER OT. LBS. 

['Juue7 22.66 17.5 19.77 15.77 18.16 17.09 19.16 18.79 

PLOT I ■! Sept. 16 15.75 12.17 11.8 9.42 9.91 9.33 10.77 10.56 

[ Loss 6.91 5.33 7.97 6.35 8.25 7.76 8.39 8.23 

[June 7 24.93 19.26 24.32 19.4 20.08 18.9 19.37 19 

PLOT II-! Sept. 16 18.43 14.24 15.03 11.99 12.62 11.88 9.8 9.61 

[Loss 65 5.02 9.29 7.41 7.46 7.02 9.57 9.39 



From this table it appears that each volume of soil four feet 

long and one square foot in section lost the amounts of water 

which follow: 

Plot I Plot II 

LBS. LBS. 

Loss of water in soil 27.67 28.84 

Rainfall from June 7 to Sept. 16 64.72 64.72 

Total loss 92.39 93.56 

17.76 inches 17.99 inches 

The amount of dry matter produced in these cases was, for 
Plot I, 450.18 pounds; Plot II, 455.36 pounds, making a yield per 
acre of 9,727 pounds and 9,840 pounds for the two plots respectively. 

Were it admissible to assume that the percolation of rain- 
water below the zone of root action had been exactly equaled by 
the rise of water into it by capillarity from the subsoil below, it 
would follow, from the observed losses of water and yields of dry 
matter, that the amount of water used for a pound of dry matter 
under these field conditions was 413.7 pounds for Plot I, and 414.2 
pounds for Plot II. 

The results of a trial similar to the one just described, and with 
the same variety of corn, for the year 1891, gave 309 pounds of 
water for one pound of dry matter, on ground which had been given 
a dressing of farmyard manure, and 333 pounds of water for a 
pound of dry matter on land which had not been manured. Here 
we have two trials by pot culture, where everything was under 



*-Eighth Annual Report Wisconsin Experiment Station, p. 123. 



Water Used hij Plants 23 

control, and there could be no percolation, which gave an aver- 
age of 301.49 pounds of water for a pound of dry matter. We also 
have four field trials, where there is the uncertainty of some loss 
of water by percolation and of some gain by capillarity from 
below, which gave a mean of 413.95 pounds for 1890, and in 1891 
321 pounds of water for a pound of dry matter. The amount of 
percolation during the season of 1890 was certainly greater than it 
was during the season of 1891, and this may or may not be an 
explanation of the difference in the amounts of water used per 
pound of dry matter in the two seasons. 

In the case of oats grown under field conditions and studied 
in the same manner as that described for the corn, the results 
showed 519 pounds of water for a pound of dry matter in the one 
case, and 534 pounds in another case, while the average of the 
two pot experiments was 501.47 pounds of water for one pound 
of dry matter. 

So, too, in the case of field studies with barley, we had an 
observed loss of 537 pounds of water in one case on ground which 
had been fallow, but 719 pounds on ground which had not been 
fallow, for each pound of dry matter produced ; while the pot 
culture gave a mean loss of only 401.74 pounds of water for a 
pound of dry matter. 

If we count the rainfall during the growing season and the 
difference between the amounts of water in the soil at the time 
of planting and at harvest, in the several field eases, as the 
amounts of water used by the crop, including surface evaporation, 
and then compare these amounts per square foot with those added 
to the several pots in the pot trials, we shall have results which 
are given below: 

Table, slioiving number of pounds of ivater consumed per square foot 

' Oats 

In pots In field Difference 

Mean amount of water per sq. ft.— lbs 101.98 72.98 29 

' Barley 

Mean amount of water per sq. ft.— lbs.' :..*.;v.. 79.11 58.65 20.46 

' Corn V 

Mean amount of water per sq. ft.— lbs. 137.3 63.8 73.5 



24 Irrigation mid Drainage 

From these figures it appears that while more water was lost 
in the field, for each pound of dry matter produced, than in the 
pot experiments, the amount of water used per square foot in 
the pots was in every case much greater than it was in the field. 
So, too, were the yields of dry matter, when expressed in 
units of equal areas, much greater in the pots than they were in 
the field. These relations are very suggestive, though, of course, 
not at all demonstrative, that the larger amount of water used 
per unit area in the pot experiments is to be credited with the 
larger amount of dry matter produced per unit area. The differ- 
ences are certainly in the direction we should expect if water 
plays the important part we have attributed to it, and if in the 
field experiments the several crops did not have all of the water 
they might have used to advantage. 

In 1892 pot experiments similar to those described were eon- 
ducted with barley, oats, corn, clover, and field peas, using gal- 
vanized iron cylinders 18 inches in diameter and 42 inches deep, 
placed in the field, surrounded by the field crop, and each experi- 
ment being in duplicate. The results of these trials are given in 
the table below: 

Table showing the amount of water used in producing a pound of dry matter 

in Wisconsin in 1892 

Dry matter Water per lb. of Computed yield Water 

per acre used 

LBS. INCHES 

14,196 23.52 

8,189 19 

19,184 25 

12,486 29.73 

8,017 16.89 



If, now, we express the relation between the amount of dry 
matter produced and the number of inches of water used in these 
trials and in those of 1891, it will be seen that the yields of dry 





Water used 


produced 


dry matt 




LBS. 


LBS. 


LBS. 


Barley 1.... 


.. 216.12 


.576 


375.21 


Barley 2.... 


.. 206.12 






Oats 1.... 


.. 174.6 


.3322 


525.59 


Oats 2.... 


.. 167.58 






Corn 1 


.. 235.96 


.9905 


238.22 


Corn 2.... 


.. 225.24 


.5657 


398.15 


Clover 1 


.. 337.36 


.5977 


564.43 


Clover 2.... 


.. 348 66 






Peas 1.... 


.. 155.24 


.3252 


477.37 


Peas 2.... 


.. 139.17 











8,189 


19 


4,157 


11.27 


7,441 


13.19 






14,196 


23.52 


8,190.5 


12.26 


19,845 


26.39 


7,045.3 


11.34 


19,184 


25.09 






12,496 


29.73 






8,017 


16.89 



Water Used by Plants 25 

matter per acre are measurably proportional to the amount of 
water used by the crop in producing it. These relations are 
expressed in the following table: 

. In the field " In cylinders 

Dry matter Water nsed Dry matter Water used 

LBS. PKR ACRE INCHES LBS. PER ACRE INCHES 

Oats in 1891 6,083 13.93 8,861 19.69 

Oats in 1892 

Barley in 1891 

Barley in 1892 

Corn in 1891 

Corn in 1892 

Clover in 1892 

Peas in 1892 

Now, here, in the ease of the oats, the average yield of dry 
matter per acre in the cylinders was 4,26 tons, while in the field 
it was 3.04 tons. But the soil put into the cylinders in the spring 
was the same as that in the field and contained the same per cent 
of soil moisture, but there was given to the soil in the cylinders 
1.39 times the amount of water which fell as rain upon the sur- 
rounding fields, plus the amount of water by which the soil was 
dryer at harvest than at seed-time ; and we had a yield 1.4 times 
as large. 

In the experiment with barley, we had an average yield of 
5.41 tons of dry matter per acre in the cylinders, but only 2.08 
tons in the field. There were added to the cylinders 1.63 times 
the amount of water which fell upon the field, plus the amount 
of water by which the soil was dryer at harvest than at seed-time, 
and we realized a yield of dry matter 2.6 times as large. There 
was in the field a yield of 40 bushels of grain per acre, but in 
the cylinders 104 bushels, and yet so far as we can see, the only 
advantage the barley in the cylinders had over that in the field 
was the increased amount of water added to the soil. 

In the case of corn, the yield of dry matter per acre in the 
cylinders was nearly 2.6 times as large as that in the field, and 
there was added to the soil in which this corn grew a little less 



26 Irrigation and Drainage 

than 2.2 times the amount of water which was available for the 
field crop. 

In 1893, oats used water at the rate of 595 pounds per pound of 
dry matter on a sandy soil where the yield was 1.196 pounds on 
7.069 sq. ft., making a yield of 7,370 pounds of dry matter per acre. 
But in this case the pot was a galvanized iron cylinder 6 feet deep, 
standing above the ground, so that the evaporation would neces- 
sarily be large, as the figures show it was. Expressed in inches, 
the water used was equal to 19.37 inches of rain. 

Clover, too, was grown in the usual form of cylinder in the 
ground in the field, and two crops cut from each of two cylinders, 
producing the yield and using the amounts of water stated below : 

' — First crop — > /— Second crop^ 

No. 1 No. 2 No. 1 No. 2 

LBS. LBS. LBS. LBS. 

Dry matter per acre 7,000 9,353 5,734 7,886 

Water per pound of dry matter 423.14 370.92 983.7 730.9 

It will be seen that in these cases the first crops, which were 
cut July 1, were much more economical of water used than wer^ 
the second crops, when measured by the standard of the number 
of pounds of water per pound of dry matter produced. Express- 
ing the, water used in inches over the surface covered by the 

crop, the results stand : 

' First crop ■ -—Second crop— > 

No. 1 No. 2 No. 1 No. 2 

INCHES INCHES INCHES INCHKS 

Inches of water used 13.06 15.28 24.89 25.44 

It is thus seen that the two crops of clover, averaging for 
the four cases a yield of 7.493 tons of dry matter per acre, and 
equivalent to 8.815 tons of hay containing 15 per cent of water, 
used for the season a mean of 39.33 inches of water, an amount |j 
which considerably exceeds the total annual rainfall of the year '. 1 
for this locality. 

Side by side with the clover trials of 1893, four cylinders were 
treated in the same manner for corn, all of them growing a flint 
variety. In these cases, too, one cylinder of each pair had its 



i 



Water Used by Plants 27 

soil enriched with farmyard manure, to- determine if a rich soil 
affected in any notable way the rate at which water was used in 
crop production. 

The results of these trials may be stq,ted as given below: 

' Flint corn ^ > Flint corn > 

Manured Not man'd Manured Not man'd 

12 3 4 

LBS. LBS. LBS. LBS. 

Dry matter per acre 34,730 33,620 22,540 9,505 

Water used per lb. of dry matter 223.3 232 257.4 223 

Water expressed in inches 34.23 34.42 25.56 13.06 

The difference in yield between cylinders 3 and 4 and 1 and 2 
appears to have been due to the condition of the soil at the time 
the cylinders were fitted, the soil being more moist in 3 and 4, 
which stood upon ground lower and too wet for conditions of best 
growth. The field yield of corn surrounding the cylinders, and 
with the same kind of soil, was 4.4 tons of dry matter, yielding 
66.95 bushels of kiln-dried shelled corn per acre, which is large 
for field conditions with the normal rainfall. But the mean yield 
in cylinders 1 and 2 was 17.09 tons of dry matter per acre, or 
almost four times as much, while the average of the four cylinders 
was 2.85 times as large, but using 2.2 times the amount of water 
which fell upon the surrounding fields as rain during the growing 
season for this corn. 

It does not, of course, follow from these experiments that well 
tilled field soil, if irrigated properly, will produce such yields as 
these which have been recorded ; neither does it follow, neces- 
sarily, that these large yields owe their excess over normal crops 
only to the extra supply of water added at the proper times. 
It does, however, follow from these experiments, we think, that 
were our water supply under better control and larger at certain 
times than it is in Wisconsin, our field yields would be much 
increased, if not actually doubled. It does follow, also, from 
these experiments, that well drained lands in Wisconsin and in 
other countries having similar climatic conditions are not supplied 
natui'ally with as much water during the growing season as most 



28 



Irrigation and Drainage 



crops are capable of utilizing, and, hence, that all methods of till- 
age which are wasteful of soil moisture detract by so much from- 
the yields per acre. Indeed, what we call good average yields 
per acre are determined, in a large measure, by the amount of 
soil moisture which the land is capable of turning over to the 
crops growing upon it. 

In 1894, work similar to that described was done with pota- 
toes, eight cylinders being used, two of which were placed in the 








Fig. 2. Potatoes grown in cylinders to determine the amount of water 
used in producing a crop. 

field, as already described, and six others were kept standing upon 
the surface of the ground, shaded on the south side from the sun 
in the manner represented in Fig. 2, which shows the potatoes as 
they appeared when growing. In the same year, oats were agai? 
grown in four other cylinders surrounded by field grain of t' 
same kind, and in pots with their tops flush with the top of i ^ 
ground. A statement of the results of these several trials ib 

here given. 

We give, in the first place, in illustration of the rate at whic 
potato plants use water in the various stages of their growth. 



Water Used by Plants 



29 



table showing the times of watering and the amounts of water 
^iven through the whole growing season for the crop : 

Table showing the times of watering potatoes, and the amounts of 
ivater given 



-In field — 



Cylinders above ground- 



No. 1 

LBS. 

Weights at start 504 

May 15, water added 

June 4, " " .. 10 

June 13, " " .. 10 

June 21, " " .. 13 

June 25, " " . . 10 

June 30, " " .. 10 

July 2, " " .. 10 

July 5, " " .. 15 

July 9. " " .. 20 

1 Tuly 12, " " .. 20 

July 16, " " .. 15 

July 20, •' " :. 15 

July 24, " " .. 10 

luly 28. " " .. 15 

Vug. 2. " " .. 10 

Vug. 10, " " .. 15 

A.ug. 16, " " 

iUg. 25, ' " 

Weights at close 481.7 

Total water added 198 

Soil water used 22.3 

i Dry matter 5 

Total water 220.8 

Water used, in inches. 24.02 



No. 2 

LBS. 
506.7 

10 
10 
13 
10 
10 
10 
15 
20 
20 
15 
15 
10 
15 
10 
20 



492 
203 

14.7 

.5 

218.2 

23.74 



No. 1 
LBS. 

581 
19.8 

10 
10 



No. 2 

LBS. 

576.5 

18.4 

10 
10 



10 
10 
10 
12 
10 
15 
8.9 
15 
10 
9.8 
10 

8.1 
554 
168.6 
27 

.3 
195.9 
21.31 



10 

10 

10 

12 

10 

15 
7.1 

15 

10 

22.7 

10 

21.4 
527.8 
191.6 

48.7 

.5 

240.8 

26.2 



No. 3 
LBS. 

579.6 
18.2 

10 
10 



No. 4 
LBS. 
579.7 

17.8 

10 
10 



10 

10 

10 

12 

10 

15 
5.2 

15 

10 

18 

10 

20.9 
531.6 
184.3 

48 

.5 
232.8 

25.33 



No. 5 
LBS. 
582 
17.9 

10 
10 



10 

10 

10 

12 

10 

15 

10.6 

15 

10 

18.3 

10 

16.9 
528.8 
185.6 

50.9 
.5 
237 

25.78 



No. 6 

LBS. 

579.5 

18.3 

10 
10 



10 

10 

10 

12 

10 

15 

12 

15 

10 

15.1 

10 

10.3 
545.5 
177.9 

36.5 

.4 

214.8 

23.27 



10 

10 

10 

12 

10 

15 
6 

15 

10 

21.7 

10 

22.1 
521.4 
190.1 

58.1 

.5 

248.7 

27.06 



The potatoes in the two field cylinders matured first, and were 

iug on Aug. 25, while the others stood until Sept. 21. It should 

e stated in this connection that all of the potatoes, including 

.se in the field, were affected by the hot weather blight, so that 

.n no case were the plants in full vigor and presenting the normal 

^amount of foliage to the atmosphere. 

•Y The yields of tubers in the several cases, and the computed 

W ields per acre, figured as proportional to the surface and vol- 



30 



Irrigation and Drainage 



Time of soil in which the crop grew, are given in the table be- 
low: 

Cylinders in the Ground 

' Weight of tubers ' Yield per acre- ^ 

Merchantable Merchantable 

tubers Small Total timbers Sni. 11 Total 

LBS. LBS. LBS. BU. BU. BIT. 

No. 1 1.308 .386 1.694 537.3 158.5 6958 

No. 2 .817 .775 1.593 335.6 318.3 653.9 

Cylinders above Ground 

No. 1 452 .539 .991 185.6 221.5 407.1 

No. 2 379 .792 1.171 155.7 325.5 481.2 

No. 3 322 .875 1.197 132.4 359.2 491.6 

No. 4 1.024 .314 1.338 420.6 128.9 549.5 

No. 5 709 .282 1.091 291.2 1.56.9 448.1 

No. 6 681 .435 1.116 279.9 178.8 458.7 

It will be seen from the relation between the weights of small 
and merchantable tubers that the blight referred to had exerted a 
very appreciable influence on the crop in all of the cases, so that 
the relations which exist between the water used and the dry 
matter produced cannot be regarded as normal. These relations, 
as they were found to stand, are given below: 

Table showing the pounds of ivater used by potatoes in producing a pound 
of dry matter in tuber and vine in Wisconsin during the season of 1894 





Dry matter 


"Water per lb. of 
dry matter 


Computed yield of 
dry matter per acre 


Water used 




LBS. 


LBS. 




LBS. 




inches 


No. 1.... 


513 


430.4 




12,6.50 




24.02 


No. 2.... 


5258 


415 




12,960 




23.74 


No. 1.... 


.3338 


5869 




8,248 




21.31 


No. 2.... 


5007 


480.9 




12,340 




26.2 


No. 3.... 


4505 


516.8 




11,110 




25.33 


No. 4.... 


5020 


472.1 




12,370 




25.78 


No. 5.... 


3596 


497.3 




8,865 




23.37 


No. 6.... 


5425 


458.4 




13,370 




27.06 



It is evident from this table, whatever may be said in 
regard to the yields, that the potatoes did use a very large amount 



Water Used hij Plants 31 

of water, although it was unquestionably less than it would have 
been had the plants not been affected by the blight. As it was, 
the plants received an average of 24.6 inches, which is three times 
the amount of rainfall during their season of growth. 

It should be said further, in regard to the amount of water 
used this season, that the whole of the watering was from the 
bottom, so that the surface of the ground was kept dry throughout 
the time. In order to introduce the water at the bottom, a layer 
of sand was first placed in each cylinder before the soil was filled 
in, and then a column of 3-inch drain tile was set up against one 
side, reaching from the bottom to the top of the cylinders, and in 
adding the water it was poured into these tiles. 

In the case of the cylinders of oats which were grown in 1894, 
they were watered in the same manner, so that in these cases 
nearly all of the water used did actually pass through the plants. 

The results with the oats are given below: 

No. 1 

LBS. 

Amount of water used 282.8 

dry matter produced . . .5235 

water per lb. of dry 

matter 540.6 

* ' " dry matter per acre . . . 12,900 

IN. 

Total water used, in inches 30.77 

If reference is made to the yields of 1891 and 1892, which have 
been given on a preceding page, it will be seen that the yields for 
1894 have been decidedly larger than they were in the former 
cases, but so were the amounts of water used by the plants. The 
mean of the three earlier trials gives a yield of 8,525 pounds of dry 
matter per acre, using 19.345 inches of water to produce it; but 
in these last cases the mean yield of dry matter was 11,870 pounds 
per acre, and the water used to produce it was 31.08 inches. The 
yields of 1894 average 1.39 times the earlier ones, and the amount 
of water used in producing this greater yield was 1.06 times the 
amount required for the smaller. 



No. 2 


No. 3 


No. 4 


LBS. 


LBS. 


LBS. 


280.2 


283.3 


285.6 


.516 5 


.4198 


.4663 


542.7 


674.9 


614.7 


12,730 


10,350 


11,500 


IN. 


IN. 


IN. 


30.48 


30.82 


31.18 



32 Irrigation and Drainage 

In 1895, and again in 1896, similar experiments were carried 
on with potatoes, barley and clover, both upon very sandy soils 
and upon good clay loam. The first experiments described were 
with potatoes on very sundy soil taken from the pine barrens in 
Douglas county. Wis., and which was ouite coarse-grained and 
deficient in organic matter. 

On June 3, 1895, the three cylinders in the right of the pho- 
tograph, Fig. 2, were filled with the soil in question. Some 2,000 
pounds of this soil had been procured from the surface down to a 
depth of three feet. The first, second and third feet of the soil 
were placed in them in their natural order in the field, the third 
foot being at the bottom and the surface foot at the top, so as 
to reproduce the natural conditions as closely as possible. 

In cylinder 1, on the right, the soil was left in its virgin con- 
dition ; to No. 2 there was applied two pounds of well -rotted 
farmyard manure, and to No. 3 there were given four pounds. 
The remaining three cylinders, 4, 5 and 6, were used as checks, 
and were filled to within 5 inches of the top with good surface 
soil of a light clay loam character. In order that the tubers of 
the potatoes might develop under as closely similar conditions as 
possible, and that the surface evaporation from the soil might not 
be very different, there was placed upon the surface of cylinder 
4 five inches of the surface soil from the pine barrens, on cylin- 
der 5 five inches of the second foot, and upon 6 five inches of the 
third foot. 

In planting, one tuber of the Alexander Prolific potato was 
cut in halves and the two pieces planted, so as to give two hills in 
each cylinder. The cylinders were weighed and watered once 
each week, water enough being given to maintain a constant 
weight. 

In 1896, the cylinders were again planted in the same manner 
with Rural New-Yorker potatoes. No fertilizers were used, but the 
plants were watered twice each week, 5 pounds of water being 
given to each cylinder every Monday morning and enough more 
on every Thursday, when the cylinders were weighed, to bring 
them to a constant weight. This change was made because it 
appeared possible that the texture of the soil was too coarse to 



Water Used hy Plants 33 

permit a single watering every seven days to meet the needs of 
the plants. 

The results of the two years are given in the following table: 







1 


2 


3 


4 


5 


6 






BU. 


BU. 


BU. 


BU. 


BU. 


BU. 


Yield per acre, 1896.. 




. 513.5 


862.6 


801 


1,089 


1,119 


883.2 


" " " 189.3... 




74 
, 449.5 


450 
412.6 


284 
517 


279 

810 


416 
703 


152 


Difference , 




731.2 






IN. 


IN. 


IN. 


IN. 


IN. 


IN. 


Inches of water used, 


1896 . . 


, 25.85 


27.91 


29.07 


34.08 


32.63 


27.51 


" " " " 


189.5 . . 


10.76 


20 02 


17.65 


16 27 


20.65 


12.96 


Difference 




15.09 


7.89 


11.42 


17.81 


11.98 


14.55 



It will be seen from this table that both the yield of potatoes 
and the amount of water used are much larger in 1896 than they 
are in 1895, the average yield in 1896 being 878.1 and in 1895 
only 275.8 bushels, the former being 3.18 times the latter. The 
average amount of water used was 29.51 inches in 1896, and 16.385 
inches in 1895, the former being 1.8 times the latter. 

As a further check upon these experiments, two cylinders 7 
feet deep and 4.33 feet in diameter were filled with a local yellow 
sand, and to one of the cylinders farmyard manure was applied 
at the rate of 50 tons per acre, and to the other at the rate of 25 * 
Ions per acre. These were planted in 1895 with Alexander Pro- 
lific potatoes, seven pieces in each cylinder. The watering in 
1895 was once each week, and twice each week in 1896. In the 
latter year no fertilizers of any kind were applied, and Rural 
New-Yorker potatoes were planted instead of the Alexander Pro- 
lific. In 1895, 20.05 inches of water gave a yield of 605.5 bushels 
on the heavily manured cylinder and 563.5 bushels per acre on 
^ the other. But in 1896, when the potatoes were watered twice 
each week at the rate of 75 pounds for the lightly manured ease 
and 50 pounds for the other, the yield per acre on the lightly 
manured cylinder was only 312 bushels, and yet 40.61 inches of 
water were used; while the other cylinder gave a yield of 344.5 
bushels per acre and used 31.92 inches of water, 

C 



34 



Irrigation and Drainage 



In this case it will be seen that a decidedly smaller yield is 
associated with a much larger amount of water applied at shorter 
intervals, but why this should be does not appear, unless the 
manure had become exhausted and the plants were not properly 
fed. The vines in all cases were abnormally small, and looked 
starved. 

In the experiments with both barley and clover, the small 
cylinders were used set into the ground in the field. Two cylin- 
ders were used for the barley and four for the clover, one -half of 
them filled with the yellowish sand referred to, well manured, 
and the other filled with good soil. All the cylinders were 
weighed and watered once each week, holding them at a constant 
weight, and the results are given in the table below: 

Barley, 1895 
Sand Soil 

Yield of dry matter in tons per acre 5.02 6.32 

Bushels of grain per acre 30.47 38.14 

Inches of water 25.84 31.24 

. Clover, 1895 « 

Both crops 
Sand Soil 
First crop Second crop Water used 

Sand Soil Sand Soil inches 

Tons dry matter per acre. No. 1 . . 2.88 3.48 2.36 3.28 29.36 38.18 
" " No. 2.. 2.91 3.25 3.19 2.77 .37.15 39.91 

. Clover, 1896 

Tonsdry matter per acre, No. 1.. 1.86 2.45 4.32 3.63 22.09 19.78 

" " No. 2.. 2.09 2.9 3.62 3.29 20.87 20 48 

Mean for two years 2.435 3.02 3.372 3.242 27.37 29.59 



The mean annual yield of clover on the sand for the two years 
was 5.807 tons of dry matter per acre, using 27.37 inches of 
water, and the mean product for both crops on the good soil for 
the two years was 6.262 tons of dry matter per acre, usiug an 
average of 29.59 inches of water to produce it. 

In addition to the field results which have now been presented, 
measuring the water used in the production of crops in Wisconsin, 
we have obtained some results in essentially the same manner, 
except that the cylinders were made deep enough to contain four 



Water Used by Plants 



35 



feet of soil, and all were placed in the plant-house, arranged in 
the manner shown in Fig. 3. 

In these trials, two sizes of cylinders have been used : one 18 
inches in diameter and 51 inches deep, and the other 36 inches 




Fig. 3. Method of growing plants in plant-house to determine the 
amonnt of water used. 



in diameter and the sam.e depth. The large cylinders this year 
have been filled with a black marsh soil, and the small ones with 
a virgin soil of medium clay loam variety, taken from a second- 
growth black oak grove. 

First, the results obtained from four of the large cylinders 
sowed to oats Dec. 12, 1896, and harvested July 1, 1897, after a 
period of 200 days. The oats were sown thick, and grew very 
rank, lodging quite badly. 

The total dry matter and the total water used by the crop 
of the four cylinders was as given below: 



36 Irrigation and Drainage 

No. of cylinders 13 14 23 24 

Dry matter produced— lbs 4 3.16 4.93 4.32 

Total water used— lbs 1,808 1,668 2,061.5 1,782.5 

Dividing the amount of water used on the four cylinders by 
the dry matter produced, we get, as the mean of the four trials, 
under the conditions of the plant-house, 446.1 pounds of water for 
a pound of dry matter, and a yield of dry matter per acre amount- 
ing to 12.645 tons, which is very large, indeed. The water used 
by this crop expressed as rainfall was, as a mean of the four 
trials, 49.76 inches. Here is a depth of water used from this soil 
which is a little greater than the soil itself ; but the rate at which 
the water was used, it will be observed, is less per pound of dry 
matter produced than that for the out-of-door experiments. 

In the case of the clover on these black marsh soils, there 
were eight of the large cylinders used, in four of which medium 
clover grew, and on the other four alsike clover. These were 
sown without a nurse crop, and at the same time as the oats, but 
were cut July 8, so that the period of growth was 207 days. The 
results obtained here with medium clover were as stated below : 

No. of cylinders 15 

Dry matter produced — gms 507 

Water used— lbs 673.5 

Dividing the total amount of water used on the four cylinders 
by the total dry matter produced, we get 582.9 pounds of water 
as the amount used per pound of dry matter. In this case the 
yield of dry matter per acre was 3.92 tons, equal to 4.61 tons 
of hay containing 15 per cent of water. The amount of water 
used, expressed in inches, was 20.16. 

The alsike clover gave yields and results as follows : 

No. of cylinders 17 18 19 20 

Dry matter produced— gms 628 616 576 634 

Water used— lbs 809 758 774 804.5 

In this case, the mean amount of water for a pound of dry 
matter was 581.5 pounds, and the yield of dry matter per acre 



16 


21 


22 


608 


620 


573 


795.5 


819 


678 



72 


73 


74 


75 


76 


77 


315.5 


252.4 


230 


212.5 


214.5 


222.5 


350 


206 


297 


292.5 


318 


295.5 


79 


80 


81 


82 


83 


84 


223.5 


284.5 


292.6 


284.2 


277.5 


266.5 


300.5 


311.5 


290 


326.5 


336 


347.5 



Water Used by Plants 37 

was 4.168 tons, equal to 4.9 tons of hay containing 15 per cent 
of water. The water used, expressed in inches, was 21.43. 

In the trials of clover on the virgin soil in the plant-house, 
14 cylinders of the smaller size were used, and these were seeded 
Dee. 12, 1896, and cut July 8, 1897. The yield of dry matter in 
these cases per unit area was much heavier than on the black 
soil, the amounts standing as below: 

No. of cylinders 71 

Dry matter— gms 312.5 

Water used— lbs 373.5 

No. of cylinders 78 

Dry matter— gms 303.5 

Water used— lbs 351.5 

The total amount of water- free dry matter produced on all 
the cylinders was 3,724.2 gms., or 8.215 pounds., using 4,496 
pounds of water, or at the rate of 547.3 pounds for one pound 
of dry matter. The average yield of water-free dry matter per 
acre was 7.23 tons, equal to 8.51 tons of hay containing 15 per 
cent of water. The water used during the 207 days from seed- 
time to cutting of the first crop was 34.93 inches. 

Side by side with the cases now cited, six other cylinders 
were planted to Rural New-Yorker potatoes on the same date. 
These were dug July 2, and the photo-engraving, Fig. 4, shows 
the crop produced. Although the potatoes were planted Dec. 12, 
they did not come up until into February, apparently for no other 
reason than that the tubers needed a certain period in which to 
develop the conditions for growth, which at the time of planting 
they had not had. When the plaints did come up they grew very 
rapidly. Below are given the results of these trials: 

No. of cylinders 65 

Weight of tubers— gms 1,288.7 

Bushels per acre 1,168 

Total dry matter— gms 342.6 

Water per lb. of dry mattei* 275.4 

Water used by crop — lbs 208 

Inches of water 22.63 



66 


67 


68 


69 


70 


808.1 


1,376 


1,313.4 


1,275.4 


1,204.8 


732 


1,249 


1,189 


1,155 


1,091.5 


263.6 


332,5 


334 


312.2 


328.8 


347.6 


281.7 


272.3 


307.3 


306.3 


202 


206.5 


200.5 


211.5 


222 


21.98 


22.47 


21.81 


23.01 


24.15 



38 



Irrigation . and Drainage 



Here, again, if we figure the yield of dry matter per acre on 
the basis of the amount of ground occupied, we shall have the 
large crop of 8.67 tons of dry matter per acre, using in its pro- 
duction 22.67 inches of water. 

In twenty other 18-inch cylinders in the plant-house, a variety 
of white dent corn was grown, four plants in a cylinder. These 




Fig. 4. Crop of potatoes using from 272-347 pounds of water for 1 
pound of dry matter. 

were planted May 22 and harvested Aug. 23, and on the twenty 
cylinders, aggregating 35.34 square feet of soil, 18.1 pounds of 
dry matter were produced, which used 5,685 pounds of water in 
coming to maturity, or at the rate of 314.1 pounds of water for 
one pound of dry matter, and a depth of water, when expressed 
as rainfall, of 30,93 inches, the yield per acre being 22,310 pounds 
of water -free matter. 



Amount of Wafer Used by Plants 89 

VARIATIONS IN THE AMOUNT OP WATER USED 
BY PLANTS 

It is a matter of very fundamental ipiportanee to know what 
factors or conditions may cause a variation in the amount of water 
whicli is necessary to produce a ton of dry matter, because it is 
only by knowing these that it will be possible to lay down any 
genei'al principles for determining the amount of water which 
will be required to produce a given yield. 

If we examine the data which have been presented, it will 
be observed that not only is there a rather wide variation in the 
amount of water used by different crops, but, also, that there is, 
further, a wide difference recorded as occurring with the same 
species or variety, sometimes with the same species in the same 
year, and sometimes for different years, and it is important to 
know to what these differences are due. 

In the case of corn, for example, where we have grown it 
under the cylinder conditions in the field, the following varia- 
tions have been noted : 

In 1891, Pride of the North dent corn used in one case 295.95 
pounds of water for a pound of dry matter, and in the other 307.03 
pounds. But in the first case more dry matter was produced by 
the individual plants, the first producing 4.369 per cent more than 
the other did, but in doing this only .602 per cent more water 
was taken ; that is, the most vigorous plants have produced the 
most dry matter when measured by the amount of water used. 
Indeed, it may be laid down as a general rule, that the more 
favorable all conditions are for plant growth, the more effective 
will be the water supplied to the crop. Good management, there- 
fore, will look closely to all details, even to the minor ones, 
for everything counts in plant feeding just as it does in animal 
feeding. 

Not all varieties of the same species of plant use water in 
the production of dry matter with the same degree of effective- 
ness. In our work with dent and flint corn, for example, we have 
found, as a mean of four trials, that Pride of the North dent 



40 Irrigation and Drainage 

corn used water at the rate of 309.84 pounds of water per pound of 
dry matter produced, and 25.74 inches of water when measured 
in depth on the area occupied. But four trials with a variety of 
flint corn gave a mean of 233.9 pounds of water per pound of dry 
matter, which is 75.94 poinds or 32,5 percent less than in the case 
of the dent variety. This is not because actually less water was 
used per unit area, for the flint corn in these four trials did use 
a mean of 26.82 inches against 25.74 for the dent corn. 

It seems not improbable that this more economical use of 
water by the flint corn may be in part due to its lower habit of 
growth and the greater abundance of foliage closer to the ground, 
for it may be expected that the lower position of the leaves, and 
their crowding as well, would tend to lessen the amount of 
evaporation in a given time. But to whatever the difference may 
be due, it is plain that on light soils and wherever the water 
supply is limited, larger returns may be secured by paying atten- 
tion to the variety of plant grown. 

The amount of water used by a particular crop might be 
expected to vary with the humidity of the season and the amount 
of wind movement during the period of growth of the crop ; but 
the data obtained do not appear to show so marked a relation as 
would seem should exist. The mean relative humidity of the air 
at Madison at 2 p. M., in 1891, for June, July and August, was 
63.66 per cent, while in 1892, for the same time of day and period, 
the mean was 68 per cent ; and the total wind movement for 
Madison, these years, for the three months, as given by the 
records of the Washburn Observatory, was 20,712 miles in 1891 
and 18,870 in 1892. But in 1891, 26.39 inches of water gave a 
yield of dry matter per acre of 19,845 pounds, and in 1892, 25.09 
inches gave a yield of 19,184 pounds of dry matter per acre of 
corn in the plant cylinders in the field. The differences in the 
amounts of water used during the two years, it will be seen, is 
very small, especially when it is recognized that in 1892 the dry 
matter produced, and presumably the evaporation surface also, 
was less than in 1891. 

So, too, in the case of oats for these two years, 19.60 inches 
of water gave 8,861 pounds of dry matter per acre in 1891, and in 



Amomit of Water Used by Plants 41 

1892, 19 inches gave 8,189 pounds, leaving the rate of evapo- 
ration from the plant surface very nearly the same for the two 
seasons, in spite of the differences of humidity and of wind 
velocities. 

In the case of barley for these two years, there was a wide 
difference in the amount of water used per unit area, 13.19 inches 
being used in 1891 and 23.52 inches in 1892. But the yields of dry 
matter per unit area were also widely different, being 7,441 pounds 
of dry matter per acre in 1891 and 14,196 pounds in 1892. The 
barley in 1891 used 3.54 inches of water per ton of dry matter, 
and in 1892, 3.31, or only .23 inches less, which is small. 

Even when the conditions are as different as those in the 
plant-house and the open field, the differences are not as marked 
as we were led to expect, as the table which follows will show: 



' 




In field > 1 In plant-house v 






Acre-inches of water 


Acre-inches of water 


No. 


of trials 


per ton of dry matter No. of trials 


per ton of dry matter 


Maize 


8 


2.433 44 


2.386 


Oats 


8 


5.011 12 


4.535 


Clover. .. 


24 


5.345 22 


5.005 


Total 


40 


Mean 4.263 Total 78 


Mean 3.975 



If the results are expressed in pounds of water used per 
pound of dry matter, then they stand as follows : 

Pounds of water per Pounds of water per 

No. of trials pound of dry matter No. of trials pound of dry matter 

Maize.... 8 275.6 44 270.3 

Oats 8 567.8 12 490.6 

Clover... 24 605.5 22 567.1 

Total 40 Mean 483 Total 78 Mean 442.3 

The tables show that in the case of these crops — maize, oats 
and clover — they have used in the field .288 acre -inches of water 
more per ton of dry matter produced than in the plant -house ; or, 
when expressed in the other way, 40.7 pounds of water per pound 
of dry matter more in the field cylinders than in the cylinders in 
the plant-house. Expressed in percentages, the field conditions 
demanded 9.2 per cent more water when the cylinders stood out- 



42 h^rUjaiion and Drainage 

of-doors, with tho }>l;iiils surrouiultHl by the tichl crop aiul iiuder 
the out-of-door meteoi'olojj:ical conditions, than they did in the 
house. 

This difference, liowever, shows hir^er than it really is, for it 
1ms been shown that tlie use of water is usually more economical 
in tliosti cases in which the yields are lar<^est, and in these cases 
thei-e liiis been a larfj^iu' yield of dry matter i)or unit an^a in the 
])hint-house cylind«n-s than were secui-cd from tlu^ cylinders in the 
ti(*ld. The total mean yield per aci-e for the oats, nmize and 
clover in the lield cylinders was (JJH'J tons and in tho ]>l!int-liouse 
1 .'.Vdl tons of dry matter per acre, making the latter yields on the 
average 17.19 per cent larger; and to this difference in yield must 
certainly be ascribed a part of the difference in the amount of 
water given off from the plants and from the soil during the 
periods of growth. It is quite i)lain, for example, that the loss 
of water from the soil surface would tend to be relatively larger, 
and probably, also, absolut(dy larger from the cylinders bearing 
the snnilh'st crop of a given kind. The absolute loss would cer- 
tainly ]>e largest from the cylinders where the crop had the thin- 
nest stand on the ground, and some of the cases of larger yield 
per unit area in the ])liiiit -housi^ are due to the fact that more 
phuits occupied llie same iU'(>a. 

While, therefore, from the general principles govei'uing the 
rate of evaporation, we are led to expect that more moisture must 
be lost from vegetation growing in a dry atmosphere than under 
more humid conditions, we are not able to point to our data as 
bearing out such a view in any emphatic manner. The rate of 
air movement in the plant -house has certainly been less than it 
was in the field, but the higher temperature in the plant-house 
has probably left the air relatively dryer during both day and 
night than in the iield. 

The conditions which did exist, both in the plant -house and 
in a tield of maize, were noted on July 27, 28 and 29. The rela- 
tive humidity of the air was measured with a wet-and-dry bulb 
thermometer, and the rate of evaporation was also measured under 
the two conditions with a form of Piclie evaporometer. Two of 
these instruments were hung among the corn plants in the plant- 



Amount of Wider Used ht/ Plants 43 

house iind two others in the (iel<l, one jtiiif on irri^atod gi'ound 
and the other on ^m-ouikI not irri^';i,t(Ml. 

The tabhi Ixilow shows the ViU'i:it ions in tlu) nite of (!VJii)or.i- 
tioii obaei'vod in the three loealities : 



IM;iiit, liousd 


\vviiiid 


0(1 fi(ll<l 


P: 


iold not 


irriKatod 


No. 1 No. 'J 


No. 1 


No. 2 




No. 1 


No. 2 


C. C. C. (!. 


c. c. 


c. c. 




('.. ('. 


C. <!. 


7 r>.H 


«.:{ 


4.o:{ 




(i.8() 


4.2 


r..7r> 4.:ir. 


2.'.)'} 


:i.i:{ 




4.H7 


:(.()() 


n.jct :>.() 


r).!»() 


.^).7 




(i.l 


r).7() 


().o:t.^) r).-2r> 


4.!)H 


4.2H7 




5.94 


4.:{4 



July 27 ... . 

July 28 ... . 

July 2i) .... 

Mean. 



These rates of evaporation took place ny)on a surface of 27 
square inches of wet filtfu- pnjxtr. 

The relative humidity observations were as here jijiven: 

I'lanL-hous(* IrriKutod Hold Fidld not irrigated 

I'KIt CKNT IMOli eiCNT I'Klt OKNT 

July 27 'M 45 51 45) 5:* 

July 28 :{9.5 54 55 57 02 

July 29 41 49 52 48.5 49 

Moan :«>.5 49.:{ 52.7 51.5 55.:! 



So i'ai- as these* (inures niiiy be relicMl ujx)!), it would :ii)pear 
that the rate of eviiporation in the plant-house may even have 
exceeded that in the fiehl, and if this was true durinj.? the time the 
dry matter of tlm phuit-house (ixpcM'iments Wiis bein<^ produced, 
tluMi th(} indications iii-e still Iciss marked jtointinji: toward an 
increase in the amount of waier Ix'in^ re<iuired for a ])ound of 
dry matter in a dry, rai)idly chaiij^inj? atmosphere, than is 
required under stiller and more humid conditions. 

It may be true that in the dry air a more rapid loss of mois- 
ture from the plant does take i)lace, and that this loss stimuliites 
a proportional incrense of dry matter. This is mei-ely a suppo- 
sition, however, with no experimental evidence to bear it out, 
but such a tendency would ^ive relations approaching^ those 
recorded above. So, too, if the rate of evaporation is automatic- 



44 Irrigation and Drainage 

ally controlled by changes in the transpiring surfaces of plants, 
and if this control is sensitive, then there would also be a ten- 
dency to cause the amount of water necessary to produce a pound 
of dry matter in a given species of plant to remain nearly con- 
stant under wide ranges of climatic conditions. That most land 
plants are provided with organs which modify the rate of trans- 
piration has been long established ; but how narrow the limits 
of control are remains to be demonstrated. It is fundamentally 
very important that such facts as these should be established, for 
they are needed in order that we may know how much land under 
a given crop a given quantity of water will irrigate. 

We have, at this writing, just completed a set of observations 
bearing upon this fundamental problem, and although they are 
not sufficiently extended to be demonstrative, they are yet very 
suggestive, and will be of interest here. 

If it is true that plants lose little moisture except through 
their breathing pores, and if these are closed during those times 
when there is not sufficient light to allow carbonic acid gas to be 
decomposed by the plant, then during the night, and perhaps, 
also, during cloudy weather, plants should lose but little moisture 
through their surfaces. To test this question, one of the small 
cylinders in the plant- house, containing four fully grown stalks 
of maize, was hung upon the scales, to be weighed hourly dur- 
ing the day ; and by the side of it was set a Piche evapo- 
rometer having an evaporation surface of 27 square inches, also 
to be read hourly. Below are given the results of these obser- 
vations : 

During the day, from 8:15 a. m. until 6:15 p. m., it was some- 
what cloudy most of the time, but the clouds were not heavy, and 
there was a little sunshine through a haze from 11:15 a. m. until 
2:15 P. M. From 8:15 A, M. until 6:15 P. M. the corn and soil 
lost 3 pounds of water, and there was evaporated from the evaporo- 
meter 31.5 c. c. or 1.2 cu. in. From 6:15 P. m. until 6:45 a. m. 
the next morning, the corn had not lost enough to show on the 
scales, which are sensitive to one-half pound ; and the evaporo- 
meter showed a loss of 2.3 e. c, equal to .14 cu. in. The next 
day was bright and sunny the whole time, and from 6:45 a. m. 



Transpiration Greatest During Sunshine 45 

until 6:15 P. M. the maize lost 7.5 pounds of water and the 
evaporometer lost 67.5 e. c, or 4.12 cu. in. ; but during the night 
again the loss from the maize was too small to be measured, 
while the evaporometer showed a loss of 4.6 e. c, equal to .28 
cu. in. 

On the next day, Aug. 9, all of the cylinders in the plant- 
house were weighed during the forenoon, which was cloudy, but 
in the afternoon it cleared and the sun shone brightly. During 
the whole of the afternoon and until 9 p. m. we forced steam from 
the boiler, under a pressure of 7 to 15 pounds, into lue plant-house 
through an inch pipe wide open, and kept the house closed 
through the experiment. Steam filled the whole plant-house and 
condensed upon the glass and walls, dripping in many places from 
the roof. 

On the following morning, Aug. 10, a number of the cylinders 
were again weighed, to see if there had been any loss 46f water 
from the plants, and it was found that three of the small clover 
cylinders had lost an average of 2 pounds each, while their mean 
loss during the seven preceding days had been at the rate of 2f 
pounds. Eight stalks of maize in a large cylinder lost 7 pounds, 
while its mean loss per day had been 6f pounds. Six small cylin- 
ders, each containing 4 stalks of maize, lost an average of 4| 
pounds each, while the mean loss for the week had been 4| 
pounds. 

It thus appears that during the night and cloudy weather 
plants lose but little moisture, but that when the sun shines 
brightly, even in an atmosphere nearly saturated with moisture, 
there is a very marked loss of water from the growing plants, 
and it would appear that the amount is nearly or quite as large 
in a damp as in a dry air. These observations seem strange, 
and need to be confirmed ; but they are in harmony with our 
observations regarding the amount of water required for a pound 
of dry matter. 

If we bring together all of the observations made in Wiscon- 
sin on the amount of water used in the production of dry matter 
by plants, they will stand as in the table which follows ; 



46 



Irrigation and Drainage 



Table shoiving the mean amount of water used by various plants in Wisconsin 
in producing a ton of dry matter 





No. of 

trials 


Water used per ton 
of dry matter 

LBS. 


Water used 

INCHES 


Dry matter 
produced 

TONS 


Acre-inch 

water per t 

dry mat 


Barley . . . 


5 


464.1 


20.69 


5.05 


4.096 


Oats 


. 20 


503.9^ 


39.53 


8.89 


4.447 


Maize 


. 52 


270.9 


15.76 


6.59 


2.391 


Clover . . . 


. 46 


576.6 


22.34 


4.39 


5.089 


Peas 


1 


477.2 


16.89 


4.009 


4.212 


Potatoes. 


. 14 


385.1 


23.78 


6.995 


3.399 



Total 138 Average 446.3 



23.165 



5.987 



3.939 



In computing the results in this table, the combined area of 
all cylinders, the combined weights of dry matter produced, and 
the combined amounts of water used, have been divided by the 
number of trials with each kind of crop and the average results 
used in making the calculations. 

In considering these results, it should be kept in mind that 
the water used by the several crops is made to include that which 
was lost through the soil by surface evaporation, because it was 
not easy to measure this separately or to prevent it without intro- 
ducing abnormal conditions. It is quite certain, however, that 
during all of these trials the rate of loss from the soil has been 
somewhat less than would have occurred under the best possible 
management with field conditions. 

Attention should be called to the fact, also, that the large 
amount of water used, averaging for the 138 trials 23.165 inches, 
is greater than field conditions would demand, if nothing were 
lost by percolation, for the reason that we have planted so as to 
utilize less surface area than is the practice in the field ; and it is 
to this fact, also, that the very large average yields, when com- 
puted per acre, are due, rather than to the growth of plants of 
abnormal size. 



THE MECHANISM AND METHOD OF TRANSPIRATION 

IN PLANTS 

Since water plays so large a part in the life and develop- 
ment of land plants, and since such large quantities of it are 



Mechanism of Transpiration 47 

tised by them, it will be very helpful to know in what manner 
this water is moved through and from the plant, and just what 
part it plays in plant life. 

We may understand the essentials of this complex process 
best if we compare it with our own breathing ; for transpiration 
and ^respiration of land plants have much in common with the 
breathing of animals. Bot-h the plant and animal breathe air, and 
while breathing it, both give off large quantities of water from the 
organs of respiration."] If you hold a cold, clean mirror in front 
of a person breathing, its surface becomes at once clouded with 
the moisture from the breath. So, too, if you hold the same 
cold mirror close to the foliage of a growing plant, the moisture 
escaping from that will also cloud the mirror. 

Now, the primary object of the lungs in our case is not to 
remove water from the system, but to provide a means for oxy- 
gen to enter the blood from the air, and for the carbonic acid 
gas to escape from the blood into the air. This can take place 
rapidly, however, only when the delicate lining of the air cells 
in the lungs is kept moist ; and so the chief function of the 
water escaping from the lungs is to maintain their inner surface 
continually wet. Let the lung lining once become dry, and the 
rate at which oxygen could enter and carbonic acid gas escape 
from the blood would be so slow that life could not be main- 
tained ; and in order that this fatal accident shall not occur, the 
lung surface is placed on the inside of the chest, where the rate 
of evaporation is very greatly impeded, 

V When we turn to the breathing of plants, we find that they, 
too, are only able to accomplish that very important work as 
rapidly as it needs to be done by having a very broad surface 
against which the air may come, but so placed that it shall be 
kept always wet ; and, just as in our case, it would never do to 
have this surface exposed to the open air, so the real breathing 
surface of plants is spread out on the inside of their structure, 
where hot, strong winds can never reach it. 

In Fig. 5 is represented a piece of a barley leaf, partly dis- 
sected and much magnified, which shows the breathing surface of 
this plant, and how it is protected from excessive evaporation. 



48 



Irrigation and Drainage 



In the upper part of the figure, the under surface of the leal 
is shown covered by its skin or epidermis, through which there 
can but little evaporation take place except through the opening 
which is shown at sp and the seven others like it ; and even 

these openings or breathing 
pores are so made that they 
may be automatically opened 
wide or almost completely 
closed when the needs of the 
plant call for much or little 
air. 

In the lower part of the 
figure, the skin has been re- 
moved from the leaf, so as to 
show the actual breathing sur- 
face of the barley plant, con- 
sisting of the cells marked m, 
and which are filled with the 
green coloring matter of the 
leaf, or chlorophyll. The open 
spaces, marked i, between the 
breathing cells, are the breath- 
ing or respiratory chambers, 
which communicate with one 
another all through the leaf, 
but under the cover of its 




Fig. 5. Stmcture of barley leaf. (After 
Sorauer.) sj9 is a breathing-pore ; m, 
cbloropbyll cells ; i, respiratory cham- 
bers. 



skin or epidermis, which in various ways, by a varnish, a wax or 
a close mat of hairs, is rendered less pervious to water and 
to air. In the case of tall plants, like shrubs and forest 
trees, rising a hundred and more feet into the air, nature has 
made still greater efforts to avert the danger of plants being 
destroyed by the action of drying winds. Here we find the 
trunks and all the larger limbs thoroughly protected by a thick 
bark, through which there can but little water escape as it slowly 
ascends from the roots to the leaves ; indeed, the more detailed 
we make the study of the structure and the function of parts in 
the plant, the more plain it becomes that in naost land plants the 



Magnitude of Transpiration 49 

greatest economy is everywhere practiced in regard to the use of 
water. 

If it were true that no water need be used by plants except 
that which is assimilated during their growth and reproduction, and 
in keeping the cells distended and turgid, so that wilting shall 
not occur, then there would be little need for irrigation anywhere 
except in the most arid of arid regions, for then even the hygro- 
scopic moisture of a dry soil would be sufficient in quantity to 
supply the demands of almost any land plant. 

"\The facts are, however, that during the hours of sunshine all 
growing plants which feed directly upon soil and air must have 
their assimilating chlorophyll-bearing cells continually in contact 
with a changing volume of air, in order that the carbon, which 
makes up so large a part of their dry weight, may be obtained in 
sufficient quantity from the carbonic acid gas in the atmosphere. 
But the more recent analyses of air show that on the average it 
contains but one part of carbonic acid by weight in 2,000 parts. 
Now, how much air must a field of clover breath in order that 
it may produce two tons of hay per acre ? Let us see. 

Boussingault found by analysis that 4,500 pounds of clover 
hay harvested from an acre of ground contained no less than 1,680 
pounds of carbon, and as this was derived almost wholly from the 
carbonic acid of the air, it must have decomposed 6,160 pounds 
of carbonic acid in order to procure it. But as there is only 
one pound of carbonic acid in 2,000 of air, it follows that 
12,320,000 pounds of air must have yielded up the whole of its 
carbonic acid gas in order to supply the needed amount of carbon. 
Now, one cubic foot of air at a pressure of 29.922 inches and 
at a temperature of 62° F. weighs .080728 pounds, and this being 
true, not less than 152,600,000 cubic feet of air must have been 
required to meet the demands of this clover field for carbonic 
acid. This amount of air would cover the acre to a depth of 
3,503 feet, having a uniform normal density. 

Of course, not all of the carbonic acid in the air which 
passes across a clover field can be secured, nor indeed all of 
that which enters the intercellular air passages of the green 
parts of the plant, and hence it follows that very much larger 

D 



50 Irrigation and Drainage 

volumes of air than have beeu stated must be brought into close 
contact with the growing clover in order to meet its needs. This 
air, however, cannot come into intimate relations with the green 
chlorophyll-bearing cells of the clover in the field without of 
necessity permitting the evaporation of large quantities of water 
from the plants ; and this brings us to realize how imperative is 
the demand for water by rapidly growing crops. 

The writer has found, for example, by direct measurement, 
that the air passing three feet above a clover field, and at a 
moderate rate, even as early as May 30 in Wisconsin, when the 
air temperature is only 52.48° F., may have its relative humidity 
increased from 44 to 48 per cent by the moisture taken from the 
field ; and this means that 3,510 pounds of water are required to 
make even the observed change of humidity in a volume of 152,- 
600,000 cu. ft. of air, which is the amount required to carry to 
the clover crop its carbon, supposing all the carbon which the air 
contained to be utilized. It is quite likely, however, that the 
volume of air which did contribute its carbon to Boussingault's 
crop of clover not only exceeded fourfold the amount stated 
above, but that it also had its relative humidity raised at least 
to 94 per cent. If these suppositions are true, then the amount 
of water borne away from the plants in question must have ex- 
ceeded 176,100 pounds, or at the rate of about 40 pounds of water 
for a pound of dry matter ; but it has been shown on a preceding 
page that, as a mean of 46 trials, the clover crop did lose from its 
tissues and from the soil in which it grew 576.6 pounds of water 
per pound of dry matter produced, so that, large as are the 
figures stated above, they fall far below the actual ones. 

With these estimates and considerations before us, we can 
readily understand that one of the chief functions of water in 
plant life is to keep the tissues moist and in a suitable condition 
to carry on the process of breathing, whose primary object is to 
get the plant its carbon from the air. 

In order that the plant may utilize the carbon of the car- 
bonic acid in the air, it is necessary that this should come to 
the chlorophyll-bearing cells when there is sunshine enough to 
decompose it; and since the carbonic acid would be useless at 



Control of Transpiration 51 

other times, and since the continual ingress and egress of the air 
which brings it would entail a steady drain of moisture from the 
plant by evaporation, the^breathing pores in the leaves are usu- 
ally provided with a pair of guard cells, which are so constituted 
that they may be opened and closed, and thus exclude nearly all 
tlie air from the interior of the plant ; or, by partly closing 
them, to vary the amount of air which may be admitted in a 
given time. 

In order that the escape of moisture from the plant may be 
as little as possible when the breathing pores must be open t6 
admit air, the great majority of them are placed on the under or 
shaded side of the leaf. Thus Goodale, quoting from Weiss, 
gives in a table the number of breathing pores observed per 
square millimeter of surface on both the under and the upper 
surfaces of the leaves of forty species of plants, from which it is 
computed that, on the average in these cases, there are 209 
breathing pores on the lower side of the leaf for every 51 on the 
upper side. How numerous and how minute these openings are 
may be appreciated when it is said that in the forty cases cited 
there are, on the average, 209,000 stomata on each area the size 
of the square in Fig. 6, on the under sides of the leaves of these 
species. Taking a specific case, that of corn, Zea Mays, it is 
stated that the breathing pores number, on the under side of the 
leaf, 158, and on the upper side 94, or in all 252 for each square 
millimeter of leaf, and that the combined area of these openings 
is .2124 of a square millimeter, so that 21 per cent of the leaf 
surface of corn is made up of doorways through which air may 
reach the interior of the plant, and out of which moisture must 
escape whenever they are open. 

It is not strange, therefore, that large amounts of mois- 
ture do escape from plants while they are growing, nor that there 
has been provided a means of checking this loss as far as pos-; 
sible. 

The opening and closing of the guard cells is brought about 
by changes in the quantity of material which they contain, caus- 
ing them to open when the cells become distended and to close 
when they again become limp. Unlike the other ce*lls in the 



52 Irrigation and Drainage 

epidermis of the leaf, these guard cells of the breathing pores 
contain chlorophyll grains, and are thus able, in the sunshine, to 
decompose carbonic acid and carry on the processes of building 
plant- food ; but the very fact that food is being elaborated in 
these cells causes the sap in them to become more dense, and 
this, in its turn, causes water from the direction of the roots to 
enter these cells more rapidly than the elaborated materials es- 
cape, and so to distend them, and open wide the breathing pores 
just at the time when air should be admitted to the interior of 
the leaf. But just as soon as the stimulating effect of sunlight 
becomes too feeble to allow work to be done in them, then both 
on account of the elastic tension of these cell walls and because 
of the diminished osmotic pressure toward the guard cells, more 
fluid escapes from them than enters them in a given time ; they 
become limp, and their concave faces flatten and approach each 
other, thus shutting off the entrance of air to the interior of the 
leaf and at the same time reducing the loss of water to the 
mininum. 

Again, if the soil moisture becomes insufficient to meet the 
demands of the plant, or if hot, drying winds take away the 
moisture from the leaves faster than osmotic pressure can supply 
it from the roots, then these guard cells are in the very position to 
be most and first affected by the shortage of water, and hence are 
where they will collapse and check the loss from the leaf surface. 
But just as assimilation cannot go on in the absence of sunlight, 
so it cannot go on properly in the presence of sunshine if there 
is a great deficiency of water ; and hence we see that the guard 
cells are so conditioned that they will shut off the air from the 
interior of the plant at just those times when, if it could be 
changing, it would be doing an injury by wasting moisture, which 
is so indispensable to growth, and which it is usually really dif- 
ficult for plants to get enough of to insure their most rapid and 
complete development. 

The mechanical principle upon which the guard cells are 
opened and closed may be readily understood from Fig. 6. For 
simplicity in illustrating the principles, let A, B, C, D represent 
four views of a pair of guard cells, A being the pair with the 



Control of Transpiration 



53 



mouth open, but with their two ends abutting against each other 
and pressing firmly with their backs against the surrounding tis- 
sue of the leaf, 3-4 ; B is a cross -section of these cells along the 




Fig. 6. Diagram showing the mechanical action of guard cells in opening and 
closing breathing pores. The square shows the area of under side of leaf 
containing an average of 209,000 breathing pores or stomata. 

line 1-2 ; while C and D are corresponding views with the breath- 
ing pore closed. It will readily be seen that if the water holding 
the two cells in A and B rigid and distended partially escapes 
from them, their thin walls will then fall down and take the 
positions shown in C and D, where, as no displacement can take 
place in the directions away from the opening on account of the 
surrounding tissue, the walls must advance toward each other, 
more or less completely closing the aperture between them, as 
shown at C and D. Then, too, when the cells again become dis- 
tended and turgid, the pressure will tend to force them to take 
the circular outline shown in section at B, and as the back wall 
of the two is fixed to the tissue so as not to be able to move, 
nearly all of the motion takes place upward and downward, and 
this pulls the two faces which are not fixed away from each other 
and widens the stoma or pore. It must, of course, be kept in mind 
that the shape of the actual guard cells varies in detail in many 
ways from the diagram given, and that we have here only intended 
to illustrate the mechanical principle involved in their opening 
and closing. 

We see, then, that not only is water a very important sub- 



54 Irrigation and Drainage 

stance in the economy of plant life, and large quantities of it are 
used, but that it is so difficult to always procure enough that 
nature has provided in the organization of the plant that none 
be wasted unnecessarily. It must be very evident, also, that 
whatever we may do, in our methods for growing crops, to keep 
the plants so fully supplied with moisture that they shall be able 
to utilize, all the sunlight, — by keeping their breathing pores 
wide open, so that all air which can be used will be supplied, — 
must tend to give us larger yields. 



THE MECHANISM BY WHICH LAND PLANTS SUPPLY 
THEMSELVES WITH MOISTURE 

So long as plants maintained a simple, or relatively few-celled 
structure, and especially so long as they lived wholly or largely 
immersed in water, it was an easy matter for them to be supplied 
with as much water as they needed by simple diffusion and 
osmosis, just as the dry bean, when put to soak, swells and 
becomes turgid by the water which has been driven into its cellu- 
lar structure under the ceaseless hammering impulses of heat. 
But when the time came for plants to abandon the water and to 
occupy the land with their varied forms, and especially when that 
race began for free air and direct sunshine which led on from 
herb to shrub, and through arborescent forms to the giant forest 
trees, then it became necessary for that complex and wonderful 
system of water-works which, with its intakes in the form of roots, 
spread out in a comparatively dry, well -drained soil, is able to 
gather from off the damp surfaces of soil grains and send to a 
height of a hundred feet a stream which, when divided between 
ten thousand leaves, shall yet have volume and pressure enough 
to keep them turgid in a strong, drying wind and a hot sun. 
Man, with his mechanical skill and inventive genius, has been 
able to install pumping plants which can lift more water to a 
greater height in a shorter time ; but to do this he has been 
forced to station himself by a running stream, or to import his 
energy at a great cost ; while the land plant, independent of wind 



AhsorMng Surfaces of Roots 



55 



and water and eoal, stations itself in any fertile soil, and does its 
work with the warmth of a summer day. 

In all our problems of land drainage and irrigation, we are 
searching to better understand, and through this better under- 
standing to better meet, the conditions under which a system of 
roots can best do its work. But the foundation of such an under- 
standing should be a knowledge of the root itself, ond how it 
places itself in the soil in order that it may do its work. Let us 
attempt, then, to present in a brief form what has been learned 
regarding the essential features of root structure and root action. 

Roots have three distinct functions to perform in land plants 
having green leaves : first, to absorb moisture and the salts held 
in solution y second, to convey and deliver into the 
stem of the plant the water which has been absorbed : 
and third, to act as a support to the plant and hold 
it upright in the air and sunshine, whenever it is 
not trailing or climbing in habit, or is without 
stems. • 

It appears to be the general conviction among 
plant physiologists that only the very tip ends of 
the roots are particularly serviceable as absorbing 
agents, and that even these are serviceable for a 
short time only. Farther than this, it is the root- 
hairs which branch out in great numbers from them, 
rather than the fine roots, which are the real ab- 
sorbing surfac-es. These root-hairs are extremely 




B A 



delicate, thin-walled tubes, usually not more than of' mustard 
one-eighth of an inch long and a hundredth of an plauts,— A with 

inch or less in diameter, which stand out on the xf^ ■^■i^'' ^®.^^^^' 

' ±> witii sou le- 

root surfaces like the pile on velvet. These absorb- moved. (After 
ing root-hairs never form at the very tip end of a ^^^^^^-^ 
new advancing root, and as, according to Sachs, they die off 
after a few days, they form a brush-like covering on the root 
for a distance of half an inch to two or three inches, dying 
off behind and forming anew as the advance is made into new 
soil. In Fig. 7 are shown the roots of two seedling white mus- 
tard plants, A with the particles of soil still adhering to the 



56 



Irrigation and Drainage 



root -hairs and held in a body about the young root, while B is 
intended to show the appearance of the plant with the soil grains 
washed away. So, too, in Fig. 8 is shown the root of wheat soon 

after germination, and again four 
weeks later, after the root has ad- 
vanced into new soil, and the root- 
hairs have died away behind and 
new ones formed. 

The soil grains of a good soil 
are very small, the majority of 
them even much less than to^ of 
an inch in diameter. Indeed, in a 
heavy clay soil one -half of the dry 
weight may be made up of soil 
grains as small as 25000 of an inch 
in diameter. Now, the fine root- 
hairs make their way in between 
these minute soil grains, and even 
change their shape to fit them- 
selves closely upon their surfaces 
in many cases. 

The soil particles are them- 
selves invested with a thin layer 
of water, even in the condition 
Fig. 8. Root -hairs of wheat,— A when which we know as air-dry, and 
very young, B four weeks later, ^s these minute root-hairs apply 

(After Sachs.) ,, , i 1 x ^i j? 

themselves closely to the surfaces 

of the soil grains, they are brought into immediate contact with 
the soil moisture. Indeed, capillarity has the same tendency to 
invest the root-hairs with a film of moisture that it has the soil 
grains, and we may suppose, in the absence of direct observation, 
that the root -hairs all the time carry a film of moisture equal in 
thickness to that which invests the soil grains of like diameters, 
except in so far as the film of water is thinned out by the flow 
through the walls of the root-hairs and away through the root to 
meet the demands in the green parts of the plants. Such a thin- 
ning out of the film of water on the root -hairs does take place 




Relation of Boot -hairs to Soil Grains 



57 



so long as they are in action, and it is this very process of thin- 
ning which furnishes the conditions needed in order to keep them 
supplied with water from the surfaces of the soil grains. 

The effect of surface tension, as it acts upon the water of a 
well-drained soil, is to bring about a certain regularity of dis- 
tribution of soil moisture over the surfaces of the soil grains, 
which is determined by the sizes of the grains and by the dimen- 
sions of the open spaces between them. This condition of things 
may be represented by what is shown in Fig. 9 for a particular 
soil, in which two root -hairs have found their way in among the 
soil grains. 

To explain the action of the root, let us suppose that for 
some reason there has been no movement of soil moisture and 
no root action, so that everything has come to a condition of 
rest, and we have what answers to the condition of water 
standing in a tank where everything is still and the surface has 
become level. We may now suppose that morning has come, 
with the sun shining 
brightly, so that the 
breathing pores in 
the green parts of 
the plant have opened 
wide, making it pos- 
sible for both assim- 
ilation and evapora- 
tion to go on rapidly. 
Under these condi- 
tions the sap in the 
tissues of the leaves, 
stem and root will Fig. 9. Distribution of water on the surfaces of soil 
gradually become grains and of root hairs, e, main root; 1, air-space; 
more dense than that 2, soil grain ; 3, film of water ; hh, root-hairs. 

, . , . . . T (After Sachs.) 

which IS contained 

in the root-hairs, which are encased in the film of soil mois- 
ture. But no sooner is this condition of things established than 
water in the root-hairs will begin to move toward the root, 
stem and leaves more rapidly than the denser sap enters them. 




58 Irrigation and Drainage 

Just as soon as this happens, however, the balance between 
the motion inside of the root-hairs and that outside of them will 
be destroyed, and then more water will enter the root-hair from 
the soil than has been escaping from it into the soil in a unit of 
time. This will thin out the film of water which surrounds the 
root-hairs, and then w^ater which has been surrounding the soil 
grains, impelled by surface tension, must advance upon the root- 
hairs to make good that which has been lost ; and just so long 
as the water continues to enter the roots from the root- hairs 
faster than osmotic pressure can restore it, just so long will 
surface tension force the water from the soil grains upon the 
walls of the root-hairs. 

Not only will the water which surrounds the soil grains move 
toward and upon the root-hairs so long as evaporation is going on 
from the plant and assimilation is taking place in its cells, but 
with it will go the salts containing potash, nitrogen, phosphorus, 
and other ash ingredients of plants, which have been dissolved 
by the moisture surrounding the grains. 

In the figure the root-hair, h, h, leading out from the main 
root, e, is represented, for the sake of clearness, nearly full width 
throughout its course, and, as if it had either found or had made 
for itself, by setting the soil grains aside, an unobstructed path 
in which to develop. As a matter of fact, these root-hairs are 
obliged to work their way as best they can between the angles 
formed by the meeting of the soil grains, changing both their 
direction and their form in order to do so, and sometimes the 
spaces are so narrow or the turns so abrupt that the root-hair 
seems to have applied itself to the soil, and to have adapted its 
shape so as to more completely come in contact with the surface 
of the grain itself. 

As the water surrounding the soil grains, and which is also 
drawn out upon the root-hairs, becomes more and more ex- 
hausted, the film finally becomes so thin that the rate at which 
the water can be moved out upon the root -hairs is so slow that it 
is no longer able to meet the needs of the plant, and it wilts, 
and finally ceases to grow altogether. 

Attention should be called to the fact that fresh growing 



The Extent of Root Surface 59 

roots usually have an acid reaction, and so much so that if they 
ar } allowed to develop in contact with blue litmus paper, it is 
changed to red along the lines of contact with the root. Further 
than this, if the roots of a plant are allowed to develop in eon- 
tact with a polished surface of marble, the lines of root contact 
with it will be plainly etched into its surface. Such observations 
as these lead to the belief that the delicate root-hairs, at their 
innumerable places of contact, hasten the solution of plant-food 
from the difficultly soluble ingredients of the soil by the acids 
which permeate their walls being exuded upon the soil grains, 
and there, in conjunction with the water, being able to dissolve 
materials much more rapidly than water alone could do. 

When we reflect upon the many wide leaves with which most 
land plants are provided, we are impressed with the great extent 
of surface through which the sunshine and the air may come into 
touch with the plant. But broad as these leaf surfaces .are, they 
only in the smallest way express the real magnitude of the sur- 
face of contact, for the air actually enters the leaf and passes 
around and between and in contact witii the millions of loosely 
packed cells in every leaf, and the number of times the extent of 
the internal surface of the leaf exceeds that of its outer sur- 
face is more than one would dare to express. Then, too, to in- 
crease the contact surface for sunlight, the chlorophyll grains 
which are scattered through the interior of the cells around 
which the air can pass provide an enormous surface for the 
absorption of light. 

In the root system under ground, the extremely numerous 
root-hairs, small as they are, yet provide a surface for the con- 
tact of soil and moisture with the plant which is quite commen- 
surate with that furnished by the leaf. 

That we may the more clearly appreciate the great need 
there is for the vast extent of root surface spread out by agri- 
cultural crops, and how important it is that there shall be a 
deep, well-drained soil in which the roots may expand, let me 
give the measured amounts of water used by four stalks' of corn, 
and withdrawn by their roots from the soil, between July 29 and 
August 11. Two of the maize plants were growing in each of 



60 



Irrigation and Drainage 



two cylinders filled with soil, having a depth of 42 inches and a 
diameter of 18 inches. These four stalks of corn, as they were 
coming into tassel and their ears were beginning to form, used 
during 13 days 150.6 pounds of water, or at the mean rate daily 
of 2.896 pounds for each stalk. Had an acre of ground been 
planted to corn in rows .3 feet 8 inches each way and four stalks 
in a hill, then, with an average consumption of water at the ob- 




Fig. 10. Total root of four stalks of maize, and of oats, clover and barley. 

(Prom "The Soil.") 

served rate given above, there would have been withdrawn from 
that acre an amount of water, during those 13 days, equal to 244 
tons, or 2.42 acre-inches ; and when it is observed that this water 
was withdrawn from a soil so dry that no amount of pressure 
could express a drop of water from it, it is not strange that such 
a mass of roots as those shown in Fig. 10 should be required to 
carry away from the soil the water absorbed by the root -hairs as 



The Extent of Root Surface 



61 



rapidly as it was needed. In reflecting upon the extent of root 
surface indicated by the photo -engraving, let it be remembered 
that no root-hairs contribute to the mass of the bundle, and that 
only a part of the roots proper are there, for many of the smaller 
fibers were unavoidably broken off during the operation of wash- 
ing away the soil. 

Eeferring, now, to Fig. 11, it will be seen how completely the 




Fig. 11. Distribution of corn roots in field soil. (From "The Soil.") 

whole soil of the field is threaded with roots ; for in both cases 
two hills of corn, standing opposite each other in adjacent rows, 
are shown, and the roots meet and pass one another between the 
hills, and in the younger stage these had already exceeded a 
depth of two feet ; while in the second case, taken just as the 
corn was coming into tassel, the roots had descended until at 
this time the whole upper three feet of the field soil was so fully 



62 Irrigation and Drainage 

occupied with, corn roots that not a cube of earth one inch on a 
side existed in the three feet of depth which was not penetrated 
by more than one fiber of threadlike size. In many parts of 
the soil the roots were much closer together than thisT 

At the distance apart of planting in the field from which these 
roots were taken, there were, in the surface three feet, 40/^ cubic 
feet of soil available for each four stalks, so that by multiplying 
the 1,72S cubic inches in one cubic foot by 40%, the number of 
cubic feet of soil occupied, we get a total of 69,696 cubic inches. 
If, then, each cubic inch of this soil contained not less than one 
linear inch of thread-like root, their aggregate length could not 
be less than one-twelfth of 69,696, or 5,808 feet, which is 1.1 
miles. But this extent of root-surface does not even express the 
amount of that to which the root-hairs, which are the real absorb- 
ing surfaces, are attached ; and hence we must understand that 
the actual area of surface of root-hairs for a full-grown hill of 
corn is very much greater than would be indicated by the figures 
given above. 

Let the reader bear in mind that the corn roots here under 
consideration grew in the field under perfectly natural conditions, 
and that the cage of wire shown in the engraving was simply 
slipped over the block of soil which contained the roots there 
shown, after the corn had reached that stage of maturity. 
It should also be understood that the four stalks of corn which 
absorbed from the soil the 150.6 pounds of water in 13 days did 
it at the stage of growth represented by the oldest plants in 
Fig. 11; and further, that these were only good average plants, 
such as would make a yield of 4.5 tons of dry matter per acre. 

It may be difficult for some persons to realize how it is 
possible for the delicate roots of plants to force their way 
through the soil to depths such as are indicated by the engrav- 
ings above, especially when the subsoil is a stiff, heavy clay, as 
it ^Nas in this case. Nature's method of overcoming the diffi- 
culty, however, is simple enough when we come to understand it, 
and it is as effective as it is simple. 

The first fact which we need to understand when we wish to 
learn how a root advances through the soil, is that the soil grains 



Hoiv Roots Advance in Soil 63 

in the upper four to six feet are never everywhere in close con- 
tact with one another. There are great numbers of empty spaces 
all through the surface layers of earth, and we get a very forcible 
illustration of this fact in setting fence posts. Here we dig a 
moderate sized post hole, 2 or 2% feet deep, place a 6-inch post in 
the hole, and then scrape and ram into the same hole all of the 
dirt which was removed from it, and if the job is well done we 
have a scant supply to fill it. It is the existence of these unoccu- 
pied cavities in the soil which enables roots to make their way 
through it by wedging it aside. In a thoroughly puddled soil it 
is impossible for roots to develop, not simply for lack of air, but 
because there is no room into which it is possible to set the soil 
aside to make place for the root. When a fine-grained soil is 
thoroughly puddled, all of the small clusters of grains which in a 
soil in good tilth hold together, are completely broken down, and 
the smallest particles are packed in between the larger ones until 
its cavities are so completely obliterated that even water will 
not penetrate it ; and when this is true there is not even room for 
the root-hairs to make their way between the angles formed by 
the soil-grains, for the finest silt and clay particles have been 
forced into these to fill them up. 

The second fact needed to understand how the root advances 
itself in the soil is, that it makes use of osmotic pressure to set 
the soil grains aside. Most of us know with what force dry wood 
will expand when it becomes wet and is allowed to swell. Iron 
hoops are burst by the pressure developed. A primitive method 
of blasting rock was to drive dry blocks of wood into the holes 
and then wet them. Another method of blasting is to fill the 
drill holes with unslaked lime and then add water to slake it. In 
all of these eases, the work is done by osmotic pressure, and 
the results illustrate how very great this force is when it is 
restrained, and how thoroughly adequate it would be for the pur- 
poses of the root in setting aside the soil particles if it could make 
use of it. 

ThB method by which the root uses osmotic pressure in mak- 
ing its way through the soil may be explained with the aid of 
Fig. 12, which represents diagrammatically the tip of an advancing 



64 



Irrigation and Drainage 



root in the soil. It has been found that a short way back from the 
tip end of a growing root, there is at 1 a center of growth, where 
new cells are developed by repeated enlargements and divisions. 
On the forward or advancing side of this center the new cells 
form the root-cap, which in the figure is represented by the cells 

with heavier lines ; while 
those forming on the rear 
side of the center are fin- 
ally transformed into the 
various structures which 
constitute the body of the 
root proper. 

The root-cap is a sort 
of shield or thimble, under 
the protection of which the 
root advances to set aside 
the soil grains, and the 
method of advance is this : 
At the center of growth, 
new cells are forming and 

Fig. 12. Method by which root-hairs advance enlarging out of the as- 
through the soil. (Adapted from Sachs.) similated products which 

are being brought down 
from the g^een parts of the plants by osmotic pressure. But 
when this strong pressure drives the sap into the forming cells, 
they must enlarge just as the dry wood swells, and in doing so 
something must give way. As the body of the root is larger than 
the tip, and as it is already anchored to the soil by the root-hairs 
and any branches which may have formed, the direction of least 
resistance is forward, and the cells which are in the interior of 
the base of the root- cap are crowded forward and the walls of the 
cap are wedged outward so that the soil grains on all sides are 
displaced, making room for the end of the root proper to be built 
into it. The root-cap does not slide forward through the soil, 
shoving past the soil grains, but its outer and rear cells hold 
firmly against the earth as the root builds past them, and as fast 
as they have performed their function they die and new ones are 




How Roots Advance in Soil 65 

formed in advance. The root-cap, then, is a sort of point 
through which the root advances, and which is being continually 
replaced by a new growth. 

The increase of the root in diameter thro-ughout its length is 
produced by the addition of new cells wholly within those which 
lie in contact with the soil, and the same osmotic pressure is the 
power which is exerted outward on all sides to move the earth 
away and give room for the increase in size. 

Since this osmotic pressure in the roots of plants may be very 
great, certainly more than 100 pounds to the square inch, and 
presumably several times this amount, and since during the 
growth of the root the pressure is increased slowly, and acts 
gradually to set the soil aside, it is not difficult to see that the 
plant has chosen a method of making its way through the soil 
which is not only effective, but one which utilizes the energy and 
the materials present in a soil during the growing season with 
which to accomplish its purpose. The molecules of soil moisture 
are at once the hammer and the wedge, which are driven by soil 
temperature into the growing cells to expand them and set the 
soil aside. 



E 



Part I 
IRRIGATION CULTURE 



CHAPTER I 



TEE EXTENT AND GEOGRAPHIC RANGE OF 
IRRIGATION 

While there is no reason to suppose that the rais- 
ing of crops by irrigation on an extended scale is as 
old as agriculture itself, the methods have, nevertheless, 
been so long practiced as to far antedate authentic his- 
tory. We are told that "the numerous remains of 
huge tanks, dams, canals, aqueducts, pipes and pumps 
in Egypt, Assyria, Mesopotamia, India, Ceylon, Phoe- 
nicia, and Italy, prove that the ancients had a far 
more perfect knowledge of hj^draulic science than most 
people are inclined to credit them with." 

In a paper read before the Royal Society of New 
South Wales in 1887, Mr. Frederick S. Gipps states 
that the first artificial lake or reservoir of which we 
have authentic record was Lake Maeris, constructed, 
some historians affirm, by King Maeris, and others by 
King Amenemhet III, in the twelfth dynasty, 2084 
B. C. Its object, it is thought, was the regulation of 

(66) • 



Antiquity of Irrigation 67 

the iuundations of the Nile, with which it communi- 
cated through a canal 12 miles long and 50 feet broad. 
When the river rose to a height of 24 feet, and was 
likely to be disastrous to crops, the sluices were opened 
and the river relieved by sending the flood into this 
lake, which modern travelers give a circumference of 
50 miles ; but at times of low water, when drought 
was threatened, the gates could be opened and the 
volume of the stream reinforced by the water stored 
in this reservoir. 

Sesostris, who reigned in Egypt in 1491 B. C, is 
said to have had a great number of canals cut for the 
purposes of trade and irrigation, and to have designed 
the first canal to connect the Red Sea with the Medi- 
terranean, which was continued by Darius but aban- 
doned by him, and ultimately completed under the 
Ptolemies. So numerous are the irrigation canals of 
Egypt that it is estimated that not more than one-, 
tenth of the water which enters Egypt by the Nile 
finds its way into the Mediterranean Sea. Fig. 13 
shows Lower Egypt, with its extended system of canals 
as they exist to-day. 

The Assyrians appear to have been equally re- 
nowned with the Egyptains, from very ancient times, 
for their skill and ingenuity in developing extended 
irrigation systems, which converted the naturally ster- 
ile valleys of the Euphrates and Tigris into the most 
fertile of fields. We are told that the country below 
Hit, on the Euphrates, and Samarra, on the Tigris, 
w^as at one time intersected with numerous canals, one 
of the most ancient of which was the Nahr Malikah, 



68 



Irrigation and Drainage 



connecting the Euphrates with the Tigris. The an- 
cient city of Babylon seems to have been protected 
from the floods of June, July and August by high 




CMAU 



Fig. 13. Egyptian system of irrigation canals at the present time. (Willeocks.) 

cemented brick embankments on both banks of the 
Euphrates, and, to supplement the protection of these, 
and to store water for irrigation, a large reservoir was 
excavated 42 miles in circumference and 35 feet deep, 
into which the whole river might be turned through 
an artificial canal. There were five principal canals 
supplied by the Euphrates — the Nahr Malikah, the 
Nah-raga, the Nahr Sares, the Kutha, and the Palla- 
copus ; while the Tigris furnished water for the great 



Antiquity of Irrigation 69 

Nahrawan and Dyiel, besides several smaller ones. 
Alont^ the banks of the former of these canals fed by 
the Tigris are now found the ruins of numerous towns 
and cities on both sides, which are silent witnesses of 
the great importance it held, and the great antiquity 
of the work. It started on the right bank of the river, 
where it comes from the Hamrine Hills, and was led 
away at a distance of six or seven miles from the 
stream toward Samarra, where it joined a second 
canal. Another feeder was received 10 miles farther 
on its course to Bagdad, a few miles beyond which its 
waters fell into the river Shirwan, and were again 
taken out over a wier and led on through Kurzistan. 
It absorbed all the streams from the vSour and Buck- 
haree Mountains, and finally discharged into Kerkha 
River, but onlj- after having attained a length exceed- 
ing 400 miles, with a width varying from 250 to 400 
feet. This great canal, with its numerous branches on 
either side, leading water to broad irrigated fields, 
while it bore along its main waterway the commerce 
of those far distant days, stands out as a piece of bold 
engineering hardly equaled by anything of its kind in 
modern times. 

The Phoenicians, in the time of their zenith, were 
celebrated for their canals, used both for irrigation 
and city purposes ; and at the time of the invasion of 
Africa the Syracusan General Agathocles wrote that 
"the African shore was covered with gardens and large 
plantations everywhere abounding in canals, by means 
of which they were plentifully watered ; " and 50 years 
later, when the Romans invaded the Carthaginian do- 



70 Irrigation and Drainage 

minions, their historian, Polybius, drew a similar pic- 
ture of the high state of cultivation of this country. 

In the early days of both Grecian and Roman his- 
tory, great progress had already been made by these 
peoples in handling and convejdng water by gravity 
over long distances for domestic purposes. At Patara 
the Greeks, according to Herodotus, carried an aque- 
duct across a ravine 200 feet wide and 250 feet deep, 
constructing a pipe line by drilling 13 -inch holes 
through cubic blocks 3 feet in diameter, fitting these 
blocks together with curved necks and recesses, whose 
joints were laid in cement and held secure by means 
of iron bands run with lead. This was an inverted 
syphon, now so often used to cross a ravine or canon 
in the west, but made from stone instead of steel 
or redwood hooped with steel, so commonly used to- 
day. 

Rome was supplied with water in Nero's time by 
nine separate aqueducts aggregating a length of 255 
miles, and which delivered daily 173,000,000 gallons 
of water, which was later increased to 312,500,000 gal- 
lons. The Aqua Martia conduit, which brought the 
drinking water for the city, had a diameter of 16 feet, 
and was 40 miles long. 

When the Romans invaded France, they constructed 
great systems of water works for cities in various 
places — at Lyons, Sony, Nismes, Frejus, and Metz. 
The Nismes conduit was constructed at the time of 
Augustus, 19 B.C., and delivered 14,000,000 gallons 
per day. It is noted for the great Pont du Gard, 
which carried it across a ravine, and w^iich is spoken 



Antiquity of Irri(jati<))i 71 

of by Humble as one of the grandest monuments the 
Romans left in France. 

China, like Egypt, dates its early enterprises of irri- 
gation and transportation by water far back in antiq- 
uity, for she has numerous canals, some of them 
the most stupendous works of the kind ever under- 
taken. The Great Imperial Canal has a length of 650 
miles, and connects the Hoang-Ho with the Yang-tse- 
Kiang. It has a depth seldom exceeding 5 to 6 feet, 
and in it the water moves at the rate of 2% miles per 
hour. In its path there are several large lakes, and 
across these the canal is carried on the crest of enor- 
mous dykes. 

If we leave the Old World and come to the New for 
records of an early development of the cultivation of 
land by irrigation, we shall not be disappointed, for 
traces of an early civilization in Colorado, New Mexico 
and Arizona, and extending through Mexico and Cen- 
tral America on into Peru, are found in the ruins of 
ancient towns and irrigating canals in many places. 
When the Spaniards invaded Mexico, Central America 
and Peru, they were greatly surprised to find in these 
countries, and particularly in Peru, the land of the 
Incas, very elaborate and extensive irrigation systems, 
laid out and in actual general use by these people. 

Prescott, in his "Conquest of Peru," speaking of 
the use of water for irrigation, writes that water "was 
conveyed by means of canals and subterraneous aque- 
ducts executed on a noble scale. They consisted of 
large slabs of freestone nicely fitted together without 
cement, and discharged a volume of water sufficient, 



72 Irrigation and Drainage 

by means of latent ducts or sluices, to moisten the 
lands in the lower levels through which they passed. 
Some of these aqueducts were of great length. One, 
that traversed the district of Condesuyos, measured 
between 400 and 500 miles. They were brought from 
some lake or natural reservoir in the heart of the 
mountains, and were fed at intervals by other basins 
which lay in their route along the slopes of the Sierra. 
In their descent a passage was sometimes opened 
through rocks, and this without the aid of iron tools ; 
impracticable mountains were to be turned, rivers and 
marshes to be crossed — in short, the same obstacles 
were to be encountered as in the construction of their 
mighty roads." 

THE EXTENT OF IRRIGATION 

From what has been said regarding the antiquity of irriga- 
tion, we shall not be surprised to find that its practice has found 
a geographic range which is commensurate with its distribution 
in time. We look first to European countries, and begin with 
Italy, where irrigation certainly had a very early development, 
and has ever since been yearly practiced in rural life. 

In the valley of the Po, naturally very fertile, but made more 
so by thorough and systematic irrigation, water is extensively 
applied to almost all crops. To convey some idea of the general 
practice of irrigation in the Po valley, it may be stated that on 
August 7, 1895, while riding by rail from Turin to Milan, between 
Chivasso and Santhia, a distance of 18.5 miles, the writer saw 
water being applied to 100 different fields of maize by as many 
different parties, and the fields ranged in size all the way from 4 
to 20 acres. Wheat, barley, hemp, rye-grass, clover, rice, and 
maize are among the field crops generally and extensively irri- 
gated in this part of Italy. So, too, very extensive mulberry 



Extent of Irrigation 73 

orchards are grown for the feeding of silk worms, and these are 
set along the main and distributing canals, while the space be- 
tween them is occupied by various kinds of farm crops. 

In Sicily and throughout southern Italy, nearly all fruit cul- 
ture is carried on by irrigation, the ratio of irrigated to non- 
irrigated orchards being as 15 to 1, and it is said that 100 10 -year- 
old lemon trees, when irrigated, have yielded, on the average, 
15,000 lemons, while similar orchards under similar conditions, 
but not watered, yield, on the average, but 10,000, or one-third 
less per annum. In Lombardy, there were under irrigation, in 
1878, 2,034,000 acres; in Piedmont, 1,329,000 acres; in Venetia, 
Emilia, and other provinces, enough to make a total of 4,715,000 
acres. 

In Spain, irrigation is widely practiced, and has been at least 
since Roman and Moorish times, and the total acreage has been 
variously estimated at from 700,000 to 6,000,000, the first figure 
referring to cereals, vegetables and fruits, and the latter to forage 
plants and grass lands also. In the last edition of the Encyclo- 
pedia Britannica, the area under irrigation is placed at 2,840,- 
160 acres. 

In France, irrigation began at an early date, and in recent 
years new interest has been taken in the subject, so much so that 
in Consul -General Rathbone's "Report on Canals and Irrigation, 
1891," it is stated that during the past ten years in the Depart- 
ments Drome, Alpes Maritimes, Aude and Herault, Vaucluse, 
Basses- Alpes, Hautes- Alpes, and Loire, 41,460,000 francs were 
expended on no less than 13 different canals for waterways and 
irrigation. 

The Forez Canal,* supplied by the Loire River, and irrigating, 
it is said, 65,000 acres, was begun in 1863, and the national gov- 
ernment granted $122,200 for it, loaning the balance needed to the 
department at 4 per cent. In 1886 there were 23,000 acres served 
with 115 miles of ditches, at a cost of $9.50 per acre. The water 
is distributed periodically, through pipes carrying it to points 
most convenient for a group of farms, where it is delivered to the 



* " Report on Irrigation," to Senate. Ex. Doc. 41, Part 1, 1892. 



74 



Irrigation and Drainage 



farm laterals. The water is served once each week, on the same 
day and hour, the amount received being regulated by the amount 
purchased. The delivery commences on land farthest from the 
main canal, and each proprietor turns off the water from his lat- 
eral when he has received the amount paid for, and the next in 
order is then served. The assessment is made out by November 
1, and each irrigator is notified of the days and hours when water 
will be applied to his land. This irrigation is used almost wholly 
on meadows, and it is stated that the value of land has increased 




Fig. 14. Alpine water-meadows on tJie soutli side of the 
Simplon Pass, Switzerland. 

from $44 to $300 per acre since the development of the irrigation 
facilities. 

In Switzerland, the mountain streams and rills are used in 
very many places on meadows, and this has been done so long and 
continuously on some meadows that very decided ridges have been 
formed from the sediment moved by the water ; and we were sur- 
prised to find that, even so high up asthe south side of the Sim- 
plon Pass, meadows are regularly irrigated, even by the waters 



Irrigation in Europe 75 

which have come down from the perennial snow fields of still 
higher altitudes, as shown in Fig. 14. 

In Belgium there is a network of canals known as de la Cam- 
pine, which have an aggregate length of 350 miles, constructed 
both for navigation and irrigation purposes, at a cost placed at 
$5,000,000. This water is generally used in the irrigation of 
meadow lands, and the soil of the section is very sandy. It is 
even said to have been wholly unproductive until it was reclaimed 
by irrigation. 

The figures given by E. Laveleye will show the effect of irri- 
gation on this land. An area of 5,636 acres of barren soil, pro- 
ducing absolutely nothing before irrigation, now yields an average 
of 1.32 tons of hay per acre for the first crop, and the aftermath 
is counted worth a third as much, making the total equivalent to a 
crop of 1.76 tons per acre. 

In Denmark, too, an extensive system of 145 canals, carrying, 
in 1890, 22,000 second-feet of water, has been provided, whose 
object is to reclaim some of the sandy heath lands in Jutland ; 
and it is said that the 21,000 acres of land which has been 
brought under cultivation has increased in value at the rate of 
nearly $80 per acre. 

In Austria-Hungary, irrigation, largely meadow, is practiced 
in the Mattig valley, in upper Austria ; in lower Austria ; near 
Klagenfurth, in Carinthia ; in certain of the upper and central 
valleys in Tyrol ; in the Bistritz valley, and in the valley of the 
Elbe, in Bohemia. In these countries the water is usually taken 
from rivers, creeks, springs, and ponds, or reservoirs constructed 
to impound that which is running to waste, and is led directly 
upon the land by gravity, being taken from the natural channels 
by damming the stream until head enough has been secured to 
cause the water to discharge into the distributing canal or ditch. 

For the irrigation of small meadows, water wheels are found 
along the streams in many places, for lifting the water out of the 
channels where it runs too low to be led out in the usual manner. 
These wheels, provided with buckets, according to Consul -General 
Goldschmidt, are found in great numbers on the Eisack River, in 
Tyrol, above Bozen. - About the large cities, small gardens ar« 



76 



Irrigation and Drainage 



irrigated by pumps, worked usually by horse -power, taking water 
from wells or cisterns. In the mountainous portions of the Tyrol, 
meadow irriga>tion is said to be both very extensive and very 
ancient, and in recent times many of the old works have been 
reconstructed and new ones introduced. 

So, too, in parts of Bavaria, meadow irrigation is common, 
and at Baiersdorf, on the river Regnitz, the writer counted, in 











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Fig. 15. Wlieel for lifting water, at Baiersdorf, Bavaria. 

1895, no less than 20 of the wheels represented in Fig. 15 in a 
distance of 1/^ miles, all of them used in lifting water for meadow 
irrigation, the grass being cut and fed to the cows green. 

Even in England, there are numerous water-meadows which 
have been irrigated so long that the time at which they were laid 
out, and the canals and ditches dug, is unknown. It is thought 
that some of the English water-meadows were constructed under 
the direction of Roman engineering skill, while others have sup- 



Irrigation in Europe 77 

posed that they were introduced from the Netherlands ; but the 
fact that the character of the works bears a much closer resem- 
blance to the Italian construction, and that extensive tracts of 
irrigated land are found in the vicinity of ancient Roman stations, 
as at Cirencester, lends support to the former view. 

This water-meadow irrigation of England is largely confined 
to the southern parts of the island, as in Berkshire, along the 
Kennet ; in Derbyshire, in the valley of the Dove ; in Dorset ; in 
Gloucestershire, along the Churn, Severn, Avon, Lidden, and other 
streams ; on the Avon, Itchen, and Test, in Hampshire ; in Wilt- 
shire ; in Worcestershire and in Devonshire, where catch meadows 




Fig. 16. River and canal for water-meadow irrigation, at Salisbury, England. 

are laid out in the valleys of many rivers and brooks. In Figs. 
16 and 17 are shown two views of water-meadow construction at 
Salisbury, in England. 

If we pass to the continent of Asia, we shall find irrigation 
practiced over a wide extent of territory in many countries, but 
nowhere on so large a scale as in the ancient and modern develop- 
ments in India. How wide the extent of irrigation is in India 
may be most easily comprehended from the map, Fig. 18, where, 
from Lahore, in the northwest, to Calcutta, in the southeast, a 
distance of nearly 1,400 miles, and covering a mean width not less 
than 100 miles, a large share of the land is under irrigation. 
Other modern irrigation works are to be found at Cuttack, on the 



78 



Irrigation and Drainage 



Mahanadi River, and farther south, at various points in the Madras 
Presidency. On the western side of the peninsula, too, back from 
Bombay, both at Poona, in the valley of the Mutha River, and at 




Fig. 17. Ridged surface of a water-meadow, Salisbury, England. 

Bhutan, where there is a great dam 4,067 feet long and 130 feet 
high, which forms a reservoir for the supply of the Nira canals, 
are other extensive modern irrigation systems. The Vir weir, at 
the head of the Nira canal, is 2,340 feet long, with a maximum 
height above the river bed of 40 feet, and over this weir, at maxi- 
mum flood, there pours 160,000 cubic feet of water per second, in 
a sheet 8 feet deep over the crest. 

The number of wells used for irrigation in the Madras Presi- 
dency has been estimated at not less than 400,000, while the area 
they serve is placed at 2,000,000 acres. It is further estimated for 
the whole Indian peninsula, British and native, that not less than 
300,000 shallow wells are in use, while they serve certainly more 
than 6,000,000 acres of land. 

Referring, now, more particularly to the extent of irrigation 
enterprises in India, we learn from Richard J. Hinton's report to 
the Senate that in the Madras Presidency, with a population of 



80 Irrigation and Drainage 

over 31,000,000, the irrigation works, up to 1890, involved an 
invested sum amounting to $32,488,000, and the acreage watered 
in 1889-90 is placed at 6,000,000. In lower Bengal, the same 
year, 560,000 acres were under cultivation by irrigation ; while in 
the Soane Circle system, 2,611,000 acres were served, 1,305,000 of 
which produced rice. 

The Ganges system is among the greatest in India. The 
Upper Ganges has 890 miles of main canals, with 3,700 distribu- 
taries and 17 great dams, and serves 1,205,000 acres, the system 
costing $14,644,000. The lower Ganges embraces 531 miles of 
main canal and 1,854 distributaries, serving 620,000 acres, and 
costing $7,000,000. 

In the Bombay Presidency, in 1889-90, 839,000 acres were 
irrigated, and 915,000 acres were under the public canals, whose 
total cost is placed at $10,792,000. 

In the Punjab and Sind, many ancient works dating from the 
twelfth and thirteenth centuries are still in partial operation, but 
the great famine years of 1831--32 have brought about many 
changes and great improvements. The West Jumna canal had 
cost, up to 1890, $8,000,000, and it embraces 84 miles of main 
canal and 1,110 miles of distributaries, or 1,194 in all. This, 
with the East Jumna canal, controlled 2,000,000 acres, and 
bi'ought the Indian Government in 1889-90 a revenue or land 
tax of $96,000,000. To this same system belongs the Doab canal, 
running parallel with the Jumna river thi'ough 450 miles, and 
with its 1,112 miles of distributaries and 130 miles of main 
canals, serving 580,000 acres of land which can be cultivated. It 
is said that the total expenditure in these provinces for irrigation 
purposes is represented by $36,400,000, covering about 6,000,000 
acres, one-half of which is under irrigation each year. It is 
further represented that for 60 years these investments of capital 
have realized an annual return of 8 per cent. 

It is stated that the total expenditure under British direction 
in the Punjab, Swat, Sirhind, Sind, and the sub-Himalayan 
region, has been not less than $64,000,000, with about 2,500 miles 
of canals in operation in 1890. But, besides these, there are in 
the same districts many private canals and a very large num- 



Irrigation in Asia 81 

ber of wells, which supply from 4,000 to 6,000 gallons each 24 
hours. 

In the Indus valley, there are many small canals, ranging 
from 8 to 16 miles in length, having a sum total of 709 miles, 
which supply water to 214,000 acres. Three other important 
systems supply 411,000 acres, with a total length of channel 
amounting to 1,479 miles. The Lahore branch of the Bari-Doab 
canal irrigates 523,000 acres, besides supplying the water needed 
by 1,352 villages. The cost of these works in 1889-90 had reached 
$7,872,000, while the year's net proceeds of the water supply was 
$873,000, with an associated expenditure of $288,000. 

In the province of Orissa, with an area of 24,000 square miles 
and a population of 4,250,000, there were, in 1889-90, 511,000 
acres of land under the canal systems, ready for irrigation. 

Aside from these Anglo -Indian enterprises to which reference 
has been made, Hinton states that the native or independent 
states of India comprise two-thirds of the peninsula, and that 
their peoples are extensive irrigators. The most advanced of 
these states, viewed from the standpoint of agriculture and irri- 
gation, is Jaipur, with an area of 14,463 square miles and a 
population of 2,500,000. It has 108 separate systems of irrigation 
works, with 364 miles of mam canals and 422 miles of distribu- 
taries. In the native state of Mysore, there are 1,000 miles of 
irrigation canals and 20,000 village tanks. 

In the island of Ceylon, a decided effort has been and is being 
made to restore and to extend the ancient irrigation systems, 
which have been allowed to fall into ruin. The British authori- 
ties in 1891 had already restored 2,250 of the small and 59 of the 
large tanks or reservoirs ; they have constructed 245 wiers and 
700 miles of canals. There are now over 5,000 ancient reser- 
voirs in the island, and one king, in the twelfth century, is 
credited with having had constructed 4,770 tanks and 543 great 
canals. 

In Australia, work seems to be largely prospective as yet, with 
but few results actually attained. But there are some 500,000 
acres in Victoria to be served by irrigation works which are in 
progress. In New South Wales, the amount of land in 1891 



82 Irrigation and Drainage 

actually irrigated is said not to exceed 3,000 acres, but provision 
is being made under government aid for the irrigation of 38,000 
acres. In South Australia, there are about 5,000 acres now under 
irrigation, and a company has been organized for the develop- 
ment of an irrigation system on the Murray River, to place under 
ditch 200,000 acres. Up to June, 1891, the government had sunk 
15 artesian wells, 8 of which are flowing and yielding from 8,228 
to 3,000,000 gallons in 24 hours. These are in Queensland, and 
in the same region there are 86 private artesian flowing wells. 

In China, irrigation has a very extended and general distri- 
bution. The great canal systems are laid out primarily for 
transportation, but are used jointly and generally for irrigation 
as well. It is said the most scrupulous care is taken to save and 
utilize every source of water in cultivation ; and in southern and 
central China it is estimated than an acre of land is made to sup- 
port from three to five persons. 

In the provinces of Ningpo, Fo-Kien and Shanghai, the water 
is generally taken from small ditches led out from the streams or 
larger canals, or they are fed from springs in the hilly country. 
It is said that in very many parts almost every farm is supplied 
from canals or shallow laterals, which are 2 or 3 miles long 
and from 10 to 30 feet wide, leading out at right angles from the 
main canals, often from 200 to 400 feet apart. It se'ems, from the 
written accounts, that a large part of the water used by the gar- 
deners, and even on the small but numerous rice fields, is raised 
out of the canals and streams or ponds by a species of chain 
or rope pump, worked either by hand or by oxen, and in the 
irrigation season, when water is needed, they are run at night 
as well as day. It is even said that water for irrigating is carried 
considerable distances at times and places, in buckets on a yoke 
placed on the shoulders of men. 

In the province of Fo-Kien, where the rainfall is both quite 
large and well distributed, irrigation is still practiced, but as a 
means of insuring larger yields rather than a necessity. 

In Japan, as well as in China, irrigation is, and has been from 
time immemorial, extensively practiced, and it is estimated that not 
less than two-thirds of the 12,500,000 acres of land under eulti- 



Irrigation in Asia 83 

vation, supporting 41,000,000 people, is under irrigation ; that is 
to say, water is artificially applied to not less than 8,000,000 acres 
of land in Japan. 

On the island of Lew Chew, belonging to Japan, the greatest 
care is exercised to utilize the water of all the short streams, 
wherever they are found. On the slopes and in the narrow val- 
leys, the lands are carefully leveled by terracing, to avoid washing 
and to cause the water to spread evenly over the surface of the 
ground, and thus become most effective. On the margins of the 
terraces are slight ridges, which are given permanency of form 
by being covered with grass ; these are boundaries and foot-ways, 
as well as barriers against land washing. It is said that dams 
are not used upon the streams, but in times of high water the 
terracing has been such that the water can be at once spread out 
over the cultivated areas, and gently let down to the lower levels 
and back into the main channels, after having done its work of 
saturating and fertilizing the fields. In order that nothing shall 
be lost by way of washing, there is a lower waterway around the 
margin of the terraced areas, which conducts the water to one 
corner, where it passes to the next terrace below, but first flowing 
through a sort of settling basin partly filled with vines or rubbish, 
whose purpose it is to collect the silt, to be used in compost heaps 
for manure. At the lowermost level, before the water finally 
enters the stream, there is a larger settling basin, through which 
the water must pass and drop whatever of value it may still 
be carrying where it may be recovered and used. 

In writing of irrigation in Siam, Consul -G-eneral Jacob T. 
Child states that about one-half of that country is under cultiva- 
tion, and of this four -fifths are irrigated, much of it for rice. 
The fields are supplied with water from canals, which branch out 
from the rivers in all directions, and the main lines are con- 
structed by the general government, but those supplying the 
individual fields directly are made by the individual land 
owners. Where the land is government property, there is an 
annual rental of about 28 cents per ri, or 84 cents per acre, 
including the use of the water. 

Irrigation in other parts of Asia at the present time, as is 



84 Irrigation and Drainage 

the case both in Japan and China, is carried on in a small way 
largely by individual effort, but is widely and irregularly scattered, 
so that it is difficult to form any exact or even adequate estimate 
of the extent of such irrigation ; and the same statement is also 
true of British India outside of the organized enterprises of 
English capital. Indeed, it must be said that all through Asia 
Minor and Central Asia isolated and individual irrigation plants 
are to be found, which in the aggregate would sum up a grand 
total. Irrigation is carried on in this individual way in Corea, in 
Afghanistan, and parts of Russian Central Asia. It is even to be 
found in Thibet and on the Pamir, ''The Roof of the World," 
12,000 feet above sea level. Nor can it be said that this irriga- 
tion is carried on only in those places where water is most easily 
obtainable, for it is sometimes secured under conditions so labo- 
rious that few Americans would think of undertaking the task. In 
parts of Armenia, for example, where underground water is 
abundant, and where the ground is sloping, it is a common prac- 
tice to dig a line of wells extending down the slope and then, by 
connecting the bottoms of these wells by a tunnel leading out 
upon the surface at a lower level, the water becomes available for 
irrigation, and is collected in reservoirs, to be used as needed. 
Water is thus collected and brought to the surface of the ground 
by gravity, even in sections where the uppermost wells must be 
sunk to depths as great as 80 to 100 feet. The same practice also 
is said to exist in the mountainous parts of Afghanistan, Cashmere, 
and other parts of Central Asia, and these underground water 
channels are often of considerable length, and many miles in 
the aggregate have been constructed. 

On the continent of Africa, the most extended system is, of 
course, that found in Egypt, developed along the valley and 
delta of the Nile. Willcocks tells us, in his"Egyptain Irriga- 
tion," that the cultivated or irrigated area in this long, narrow 
valley is 4,955,000 acres, while the total area which is below the 
level of flood waters, and, therefore, capable of irrigation, is 
6,400,000 acres. This irrigated area is confined at present to a 
long and relatively very narrow strip bordering the course of the 
stream, and the naked desert sands on both sides come up sharp 



Irrigation in Africa 85 

against the watered area, which begins at Assuan, some 500 miles 
from the sea, not following the windings of the Nile. The popu- 
lation of this country is now given as 5,000,000, but it has been 
estimated that Egypt once supported 20,000,000 inhabitants ; and 
a practice of today, which will seem strange to the reader, is 
that of digging up the rubbish piles on the sites of ancient vil- 
lages, towns and cities, which represent the waste of the millions 
who have passed away, and using this as manure to fertilize the 
fields now under irrigation. The dry climate of this country has 
preserved these materials from complete decay, and the site of 
old Cairo is now being dug over to enrich the fields for miles 
around. 

The mean daily discharge of water which passes from Upper 
Egypt, at Cairo, into Lower Egypt is estimated at 8,830,000,000 
cubic feet, but as large as this amount is, it would require 20 
days to place Wisconsin under an inch of water. 

In the Algerian Sahara, since the sinking of the first artesian 
well, in 1848, at Biskra, by M. Henri Fournel, the work went for- 
ward, until in 1875 there had been 615 wells put down, having 
an average depth of 145 feet, 404 of which are in the province of 
Constantine, 194 in the province of Algiers, and 15 in that of 
Oran. A strange thing about these artesian waters is the pres- 
ence in them of nitrates, and irrigation with them has brought 
upon the desert sands wonderful oases, 43 in number in the Oued 
Rir, supporting, in 1885, 520,000 date palms of bearing age, 140,- 
000 palms from one to seven years old, and about 100,000 other 
fruit trees. 

On the south side of the equator, in Africa, there has as yet 
but little been done in the way of irrigation, although in Cape 
Colony efforts are being made. In 1889 the U. S. Consul at Cape 
Town, Geo. F. Hollis, states that the most complete storage work 
now constructed in the colony, and the most important, is that at 
Van Wyck's Vley. The rainfall in this section is very irregular, 
the average for 11 years being 10 inches. The reservoir has de- 
pended upon a catchment area of, say, 240 square miles, but this 
has been found inadequate, and a furrow is now nearly com- 
pleted to bring over water from a neighboring river, by which it 



86 Irrigation and Drainage 

is estimated that the water- covered area will be increased to 19 
square miles, with a depth of 27 feet. The land under irrigation 
is owned by the government, and is leased at a minimum rate of 
10 shillings per acre. 

In the island of Madagascar, on the east, and that of Madeira, 
on the west of Africa, irrigation is also practiced ; in the former 
for rice culture only, and by the system of flooding ; but in Ma- 
deira the system is both elaborate and extensive, covering over 
one-half of the whole island, or 120 square miles. There are no 
catchment basins or reservoirs other than those which nature has 
provided, and the water used is that which the soil collects dur- 
ing the rainy season and gives up in the form of springs. The 
water carriers have been constructed with care and skill, and 
some of them have a length of 60 or 70 miles. The thrifty 
farmers have on their lands reservoirs into which they collect 
their share of water when it is delivered to them, and from this 
distribute it to their several crops as they desire ; but the poorer 
class, who cannot afford the reservoir, are obliged to use the water 
directly as it comes to them, and as the intervals are long be- 
tween the delivery of water they are not able to make the best use 
of that which they get, and their crops suffer in consequence. 

In the Pacific Ocean, too, there are islands in which irrigation 
is practiced with great skill outside of those of Japan, to which 
reference has already been made. Among these may be men- 
tioned those of Hawaii, and the development of the sugar industry 
there has in recent years led to a corresponding development of 
the facilities for irrigation, as would be expected when it is stated 
that adequate irrigation there has increased the yield of sugar 
from 2 tons to 4 tons per acre. It is stated that there are about 
90,000 acres under cane, one-half of which is irrigated ; some 
7,000 acres of rice, and 5,000 acres of bananas, the rice being all 
under water. The water supply comes from mountain streams, 
with their reservoirs, and from springs and artesian wells. 

The artesian wells about Pearl Harbor are among the largest, 
yielding an enormous quantity of water, sufficient to irrigate 
20,000 acres of rice and a large area of bananas and other products 
besides. There have been 100 of these wells sunk about the mar- 



Irrigation in America 87 

gin of this island, 21 to 42 feet above ocean level, in the last 12 
years, and four of them are said to yield water enough for a city 
of 165,000 inhabitants. 

In the island of Java, too, irrigation is extensively practiced, 
and regarding the island of Lombock, still to the east of Java, 
Mr. Arthur R. Wallace writes : "It was here that I first obtained 
an adequate idea of one of the most wonderful systems of cultiva- 
tion in the world, equaling all that is related of Chinese industry, 
and, as far as I know, surpassing, in the labor bestowed on it, 
any tract of equal extent in the most civilized countries of Europe. 
I rode through this strange garden utterly amazed, and hardly 
able to realize the fact that in this remote and little known island, 
Lombock, from which all Europeans (except a few traders at the 
port) are jealously excluded, many hundreds of square miles of 
irregularly undulating country have been so skillfully terraced and 
leveled and permeated by artificial channels that every portion of 
it can be irrigated and dried at pleasure." 

Passing, now, to the American continent, we have already 
referred to its prehistoric irrigation works, and to the extensive 
and complete systems of irrigation found in South America before 
the occupancy of that continent by the Spanish and Portuguese, 
for irrigation was practiced there on both slopes of the great 
Andean ranges. It must be said, however^ to the shame of our 
boasted civilization, that a very large share of those extensive 
and valuable improvements have been allowed to pass into ruin, 
and now must be restored at great cost. 

In the Argentine Republic, lying between 20° and 56° south 
latitude, irrigation is being practiced in the provinces of Cordoba, 
San Luis, Mendosa, San Juan, Catamarca, Rioja, Santiago del 
Estero, Tucman, Salta and Jujuy ; and it is stated that the total 
area under cultivation by irrigation will exceed 1,759,600 acres. 
According to Consul Baker's report, works were begun about 
1882-83 on a number of large dams and canals, using the water 
of four important rivers, at an estimated cost of $15,280,000, 
which were expected to have an aggregate capacity equal to about 
3,020,000 acres. 

"While there are large areas in the aggregate irrigated in 



88 Irrigation and Drainage 

other parts of South America, Central America and Mexico, no 
very definite idea of its magnitude or distribution can be given 
as yet. 

Newell i says, in the report of the Eleventh Census, that in 
the western part of the United States the area irrigated within the 
arid and sub -humid regions aggregated at the end of May, 
1890, 3,631,381 acres, or 5,674.03 square miles, while the total 
number of farms or holdings upon which crops were raised by 
irrigation was 54,136. In this irrigation, water was supplied by 
3,930 wells to 51,896 acres, at an average cost of $245.58 per well, 
the wells yielding an average of 54.43 gallons per minute. The 
average value of products from this irrigated land per acre he 
found to be $14.89, the farms having an estimated mean value 
per acre of $83.28, while the average size of each farm or holding 
was 67 acres. The average value of the product of the average 
farm was thus $897.63. 

To bring together in close review the extent of irrigation as 
it is today practiced in the various parts of the world, we may 
quote the statements of Wilson : " The total area irrigated in 
India is about 25,000,000 acres, in Egypt about 6,000,000 acres, 
and in Italy about 3,700,000 acres. In Spain there are 500,000 
acres, in France 400,000 acres, and in the United States 4,000,000 
acres of irrigated land. This means that crops are grown on 
40,000,000 acres which, but for irrigation, would be relatively bar- 
ren or not profitably productive. In addition to these, there are 
some millions more of acres cultivated by aid of irrigation in 
China, Japan, Australia, Algeria, South America, and elsewhere." 

These figures seem enormous as we read them, and so they 
are, but they leave an exaggerated impression on the mind which 
needs to be corrected, for very few realize the magnitude of the 
volume of water which must be handled in raising a crop by irri- 
gation. In order that we may not mislead in this direction, we 
wish to make the correction. Let us suppose that the amount of 
land which is actually under irrigation at the present ti-me is four 
times the 40,000,000 of acres which have been enumerated above. 
Now, were this supposition true, and all of these acres were 
brought together in one solid square, it would have but 500 miles 



Climatic Conditions 89 

on a side. But to cover such an area as this with 2 inches of 
water once in 10 days would require more than three Nile rivers 
flowing at maximum flood— a river 50 feet deep, 1.156 miles wide, 
running three miles an hour. 

THE CLIMATIC CONDITIONS UNDER WHICH IRRIGATION 

IS PRACTICED 

If we study the conditions of rainfall under which 
irrigation has been practiced, we shall find rather wide 
variations in the mean amounts which fall upon the dif- 
ferent countries, especially when the mean annual rain- 
falls are compared. In all of India except the extreme 
northwest part; throughout China, Japan and Siam, 
in Italy, and France, and Mexico, as much rain falls 
during the year as falls in the United States east of 
the 97th meridian, if we except Louisiana, Mississippi, 
Georgia and Florida, — an amount ranging from 23.6 
inches to 51.2 inches, or between 60 and 130 centime- 
ters. But in Asiatic Turkey, Persia, Afghanistan and 
the extreme northwest of India ; in the irrigated parts 
of Queensland, Victoria and South Australia ; in Cape 
Colony, Algiers and Spain ; and in Argentina and the 
western United States, south of Washington state, the 
rainfall for the year drops from 23 inches to less than 
8 inches. On the lower Ganges, from the Soane region 
to Calcutta, and south along the east coast as far as the 
Orissa canals, the yearly rainfall is equal to that of the 
southern states, or from 51 inches to 78 inches (130 to 
200 centimeters). It is not, therefore, in regions of 
small rainfall alone that irrigation systems have been 
developed. Indeed, there must always be contiguous 



90 Irrigation and Drainage 

territory of considerable rainfall, in order to fill the soil 
and give rise to springs, streams, and wells, or there 
could be no water for irrigation. It is only the accident 
of a great stream like the Nile, gathering its waters in a 
region of large rainfall, that makes any irrigation at all 
possible in a rainless, desert country like Upper and 
Lower Egypt. 

The distribution of the rainfall with reference to the 
growing season, more than the quantity of it, is the 
chief factor in determining whether irrigation will be 
profitable or not. In the irrigated districts of Italy, 
Spain, France, Austria -Hungary, Algiers, Cape Colony, 
Asia Minor, Armenia, Victoria, South Australia, and 
the westernmost part of the United States, there is a 
tendency to a dry time in early or late summer, at the 
time when crops need water most, or in some of these 
countries it may be dry the whole season through, the 
rainy season being in fall or winter. In China, south- 
ern Japan, Siam and Ceylon the summer is rainy, but 
there is a tendency to develop a short dry season in 
midsummer. In Switzerland, Belgium, Denmark, Eng- 
land, Bavaria, Madagascar, North Japan, Queensland, 
and Mexico there is usually a uniform distribution of 
rain throughout the whole of the growing season. In 
these latter countries, however, while irrigation is prac- 
ticed in them, it must be said that it is supplementary 
rather than a necessity. 



CHAPTER II 

THE CONDITIONS WHICH MAKE I RBI CATION IMPERA- 
TIVE, DESIRABLE OR UNNECESSARY 

To understand the conditions which make it im- 
perative, desirable or unnecessary to irrigate land, it 
is important to have clearly in mind the various objects 
which may be attained by the application of water to 
cultivated fields. 

THE OBJECTS OF IRRIGATION 

The first and primary object to be attained in irri- 
gating the soils of arid climates is to establish those 
moisture relations which are essential to plant growth, 
and the same fundamental object will usually stand 
first in sub -humid climates, as it may even in those 
which are distinctly humid ; for in the sub -humid 
climates it very often happens that the intervals 
between rains of sufficient quantity are so long that 
almost any crop may suffer ; and in humid climates 
there are certain crops, like the cranberry and rice, 
which profit by more or less protracted inundations ; 
or, again, like the pineapple, growing upon extremely 
leachy sands, which can retain but a small quantity 
of water even for a single day, and where it is neces- 

- (91) 



92 Irrigation and Drainage 

sary that even frequent showers shall be supplemented 
in order that the best results may be attained. 

In the second place, lands may be irrigated in any 
climate, when it is desired to carry to the land ferti- 
lizing matter which the irrigation waters may hold in 
solution or in suspension. The extreme cases of this 
practice are where cultivators take advantage of the 
large amounts of plant -food which are borne along 
in the waters of streams into which the sewage of 
great cities, like Paris or Edinburgh, are discharged. 
Such waters are extremely fertile, even when much 
diluted. In emphasis of this fact, Fig. 19 shows a 
field of heavy grass growing on the Craigentinny 
meadows of Edinburgh. This ground yields from three 
to five such crops each year, and has done so for 
nearly a century, with no other fertilization than that 
which comes to it through the winter and summer 
application of diluted sewage water. Hence we need 
not be surprised that such lands have rented as high 
as 18 to 22 pounds sterling for the season per acre, 
when the rentals are sold at auction to the highest 
bidder. 

But ordinary river waters are widely used in vari- 
ous countries, chiefiy for the fertilization of water 
meadows. The amount of water applied in a year 
is in some sections very great, reaching, in the Vosges, 
in France, over 300 feet in depth per year. It is 
during the colder portions of the year, when the grass 
is not growing, that the larger part of the water is 
applied, depending upon the absorptive and retentive 
power of the soil to abstract from the water, as it 



Objects of Irrigation 



93 



passes over and leaches through, enough of potash, 
phosphoric acid, and other ingredients of plant-food, 
to hold the strength of the soil up to a uniformly high 
standard, even when constant cropping is practiced. 



































■ m 


■■ 




^ 


1 




-■^ftonL 


Bl^. 




1 


1 




iK^iigSi^M^.::9M 




^^^« 








i 




„ '■ ^^'Sl 


--.u>-^^^^^g^, -y 


■$;. . 


''HH^ 












1"^ 


^^^ 


^^1^^ 


pSi"' 


♦^ .- 










1 




II "' 


<>\;- 


— '^■. "'"' 


3... 




■■■^ - ■■■ 


^ "* 


i 


; 


K; 


-. 


' ' ' ^'' "- 






\\,- 


" 


°'l 




^^Bh^,''''^ " 









i ig. 19. Heavy growth of grass on the Craigeutiuny meadows, 
Edinbxu-gh, Scotland. 

A third object in irrigation, in certain classes of 
cases, is primarily to change the texture of the soil. 
When soils are very sandy and open, having so small 
a water capacity that not enough is retained for the 
growth of most crops, then the leading of the water of 
a turbid stream over such lands results in the deposition 
of silt to such an extent as, in the course of time, to 



94 Irrigation and Drainage 

very materially improve their physical condition ; but 
at the same time giving to these soils a large amount 
of plant -food, for the material borne along in suspen- 
sion in the water of rivers is usually very valuable, 
derived, as it is, from the finest and best parts of fer- 
tile soils. These ingredients of the flood waters of 
the river Nile are extremely valuable to those desert 
sands which, under the long action of strong winds, 
have lost the major part of those fine and extremely 
important grains which the sand storms of the deserts 
have picked up and swept away. 

In the fourth type of irrigation, which is an extreme 
case of the last, the aim is to flood low tracts of land 
with silt -bearing water in large volume, and to hold it 
there until the suspended matters have been deposited, 
so as ultimately to build up the whole tract, raising it to 
a level at which it may be naturally drained, or at which 
a depth of fertile soil sufficient to meet the needs of 
agriculture may be laid down over one which had been 
undesirable. Low -lying lands have been built up by 
this method until in the course of ten or a dozen years 
the whole surface has been raised as much as 5 to 7 feet. 

A fifth type of irrigation, which has received a 
notable expansion in recent years, has for its primary 
object the rapid destruction of the organic matters held 
in solution and in suspension in the sewage waters of 
cities, in order that they shall reach river channels and 
the ground -water of the surrounding country suffi- 
ciently purified not to endanger the public health by 
a pollution of drinking waters, or by developing un- 
heal thful atmospheric conditions. 



Water Needed for a Paying Crop 95 

THE LEAST AMOUNT OF WATER WHICH CAN PRODUCE 

A PAYING CROP 

In the manufacture of butter from milk, it is a mat- 
ter of prime commercial importance to know just how 
much butter -fat that milk contains, and what is the 
maximum amount of butter that fat is capable of pro- 
ducing ; for only this knowledge can show how closely 
the manufacturer is working to his possible limit of 
profit, and how great his losses may be. For a like rea- 
son, it is very important to know what is the minimum 
amount of water which, under stated climatic conditions, 
can meet the needs of a given crop, producing a paying 
yield. It is important, because only such knowledge as 
this can show how economical or how wasteful our 
methods of tillage may be, and how nearly we are realiz- 
ing the largest profits which are possible to the business. 

In the Introduction, much pains has been taken 
to give in detail the evidence, and the methods of pro- 
curing it, which shows how much water must be used 
by a given crop in coming to maturity when placed 
under the best of conditions. This has been done, 
because it is a part of the knowledge which is needed 
to show under what climatic conditions irrigation msiy, 
and under what it may not, be practiced ; because it 
is needed to show how far into the sub -humid districts 
agricultural' operations may be pushed without the aid 
of irrigation ; because it will help to teach how far we 
may hope, by the practice of the best methods of till- 
age, to dispense with irrigation, and avert disastrous 
results during seasons of drought. 



96 Irrigation mid Drainage 

We have already referred at some length to the 
seemingly small amounts of water used by the wheat 
crop in coming to maturity in the San Joaquin valley, 
in California, and to the long period of some 60 days 
at the close of its growing season during which it 
receives no water, either as rain or by irrigation. 
What is the minimum amount of water which is capa- 
ble of producing a yield of 15, 20, 30 or 40 bushels of 
wheat per acre, and how does this compare with the 
actual rainfall of the San Joaquin valley ? 

We have made no observations with wheat, like those 
which have been recorded for oats, barley, maize, clover 
and potatoes, but from similar observations made by 
Hellriegel, in Germany, it is probable that the amount 
of water necessary to produce a ton of dry matter with 
wheat is not very far from 906,000 pounds or 453 tons, 
equal to 3.998 acre -inches. How many bushels of 
wheat should this give ? 

The ratio of the dry weight of the kernels to that 
of the straw and chaff in a crop of wheat has been 
found to be as 1 to 1.1 in a dry season, but to be as 
high as 1 to 1.5 when there has not been an undesir- 
able stimulation to the growth of straw. But where 
wheat is irrigated in the southeast of France, Gasparin 
states that a ratio of 1 of grain to 2 of straw is usual. 

If we take the ratio of 1 to 1.5, and allow 60 pounds 
to the bushel of wheat, we may compute the least 
amount of water which is likely to enable a crop of 
varying yields per acre to be produced, and the re- 
sults of such a computation are given in the following 
table : 



Water Needed for a Given Crop 97 



Table showing the least amount of water required to produce different yields of 
wheat per acre when the ratio of grain to straw is 1-1.5 



, 




Yield 


per 


acre 








Wgt 


.. of grain 




Wi 


it. of straw 


Total wgt. 


Water used 


No. bushels 




TONS 






TONS 


TONS 


ACRE-IN. 


15 




.45 






.675 


1.125 


4.498 


20 




.6 






.9 


1.5 


5.998 


25 




.75 






1.125 


1.875 


7.497 


30 




.9 






1.35 


2.25 


8.997 


35 




1.05 






1.575 


2.625 


10.495 


40 




1.2 






1.8 


3 


12 



These amounts of water, given in the last column 
of the table, are so small that they appear false, for the 
quantity given for 15 bushels to the acre is almost 
covered by the rainfall of the most arid parts of the 
world. Several statements need to be made in order 
to put them in their true light. 

In the first place, the figures could only be true 
when the amount and kind of plant -food in the soil 
is all that the crop can use to advantage, for no amount 
of pure water can make up for such deficiencies except 
in so far as it makes more rapid the solution of other- 
wise unavailable plant -food in the soil. Then, again, 
the data for the table were procured under conditions 
which permitted no loss of moisture from the soil, 
either by surface drainage or by downward movements 
beyond the depth of root action. Further than this, 
no account is taken of the water which may have been 
given to the soil in bringing it to the proper moisture 
conditions previous to planting the crop in it. Water 
enough was given to the soil to put it in the right 
condition to start with, and the amounts in the table 

Q 



98 Irrigation and Drainage 

cover simply what has been found necessary to main- 
tain that amount against surface evaporation from the 
soil under the best of conditions and through the crop 
itself. In the San Joaquin valley there is a long inter- 
val, from the end of July until the fall rains begin 
in November, when some evaporation is taking place 
from the surface soil, and enough rain must have 
fallen to bring the soil up to a good standard condi- 
tion of soil moisture before the crop is started in it, 
and the amounts in the table would need to be in- 
creased by so much, at least, as would be required 
to establish this condition. 

How much water would need to be added to the 
soil in the San Joaquin valley by the fall rains, in 
order to restore the proper amount of soil water, or 
how great the evaporation maj^ be between harvest and 
seeding time, we do iiot know. We do know, however, 
that the rate of evaporation from the surface of a dry 
soil is not very rapid. In illustration of this, it may 
be stated that after removing a crop of oats from four 
of our cylinders in the field, a record was kept of the 
loss of moisture from them between Aug. 2 and Aug. 
25, and it was found that the total evaporation from 
7.068 square feet was 5.3 pounds. In another case, 
six cylinders in the field lost by surface evaporation 
between Jan. 10, 1894, and March 12, 41.8 pounds. 
The loss per 100 days expressed in inches in the first 
ease was .6268, and in the second 1.243. 

Taking the first of these two figures, which is likely 
to be more nearly true for the district in question, the 
total loss would be .79 inches, and at the second rate 



Water Needed for a Given Crop 99 

it would be 1.54 inches. It is certain that there is a 
further loss from these soils which is likely to be 
nearly if not quite as large as that computed, and that 
is the evaporation which takes place through the grain 
after coming to maturity, w^hile it is standing upon the 
ground before being cut ; for it is known that the 
movement of water through the plant does not stop at 
once when the kernels have fully matured. Further 
than this, if a considerable time intervenes between 
the time of the first rains and the germination of the 
seed, and especiall}^ if, after the grain comes up, it 
for any reason makes an abnormally slow growth, there 
will then be considerable additional losses which are 
not included in the figures given in the table ; and it 
would seem that the average necessary loss of soil 
moisture from these lands which in no way contributes 
to the growth of the crop of wheat may easily be as 
high as 3 inches. If this be true, the figures in the 
last column of the table would be nearer 7.5, 9, 10.5, 
12, 13.5 and 15 inches, respectively, for the differ- 
ent yields, than those stated. It is further probable 
that for the lighter yields, where the grain would have 
to stand thinner on the ground or else the plants be 
smaller, there would be absolutely more loss of water 
from the surface of the soil itself, and, hence, that the 
lower figures just given are likely to be found larger 
than they are there stated. 

The mean annual rainfall of the San Joaquin- 
Sacramento valley, as given by Harrington in his rain- 
fall map, ranges from 5 inches in the far south to 12 
inches in the north, this amount all falling between 



100 Irrigation and Drainage 

November 1 and May 1. Tlie tenth census gives the 
average yield of wheat per acre as 6 to 13 bushels in 
the south, and from 13 to 20 bushels in the northern 
part of the valley. The average yield in California 
in 1879, on 1,832,429 acres, is placed at 16.1 bushels 
per acre ; while it is stated that certified records of 
yields as high as 73 bushels per acre are recorded from 
areas as large as 10 acres. 

If we consider the "dry farming" sections of the 
state of Washington, where most of the wheat grown 
has been the spring varieties, sown in April, and some- 
times as late as May, and harvested in August or early 
September, we shall have the growing season more 
nearly the same as that in the corresponding latitudes of 
the humid parts of the United States. Here, too, 
the rainfall in amount is very nearly the same as that of 
the district to the south for the corresponding period of 
time, but the rains begin a month earlier and co.ntinue a 
month later, so that the amount for the year is from 8.4 
to 13.5 inches, or about 33 per cent more, while the 
mean yield per acre was 23.4 bushels in 1879, as 
against 16.1 bushels in California. There is here 
in Washington, as in California, a dry period of 
some 60 days, in which the crop is forced to come to 
maturity. 

It appears, therefore, from the observations and 
experiments regarding the number of inches of water 
which may be used in producing a ton of dry matter, 
and from practical experience in arid climates, that on 
deep, fertile soils, well managed, good, paying yields of 
wheat may be realized where the amount of rain is as 



lATie Rainfalls not Equally Prodtictive 101 

small as 7 or 8 inches, and large yields when it reaches 
12 to 15 inches, provided it has a suitable distribu- 
tion. 

LIKE AMOUNTS OF RAINFALL NOT EQUALLY 
PRODUCTIVE 

In the United States west of the 97th meridian, 
where the rainfall is notably deficient, except on the 
west side of the Cascade range in Oregon and Washing- 
ton, there are a large number of areas in which an effort 
has been made to grow crops of one kind or another 
without irrigation, and in considerable areas with 
marked success, as in the San Joaquin-Sacramento val- 
ley, in California, and in eastern Washington and 
Oregon, to which reference has just been made. In the 
sketch map. Fig. 20, prepared by Newell, the areas in 
which "dry farming," or farming without irrigation, 
has been practiced with greater or less success, are 
represented in black. It will be seen that this map 
shows a long, continuous area, just west of the 97th 
meridian, another one in California, and a third in 
Washington, besides very many smaller ones. These 
three larger areas receive very nearly the same amounts 
of rainfall for the year, but the distribution of it in time 
is very different. In California the rain all falls in [the 
six months, November to April, inclusive ; in Washing- 
ton it is from October to May, inclusive, while in the 
97th meridian region, much the larger part of the rain 
falls during the months between April and September. 
The eastern region, therefore, has its moisture well dis- 



102 



Irrigation and Drainage 







\ r — / *-^'' 

•^ lit' 



i 'An? 



.i!^ 







s. 



■I? 



Fig. 20. The dry-farming areas (in black) in the western United States. 

(After NevvelJ.) 

tributed through the growing season, while both of the 
western areas mature their crops in from 30 to 60 days 
of continuous nearly rainless weather ; and yet, if we 



Lil'e Uainfalls not Equally Productive 103 

compare the yields of barley, oats, rye and wheat in 
the three districts, taking the Tenth Census figures for 
California, Washington and Kansas for comparison, 
the yields are largest in Washington and smallest in 
Kansas, as shown below: 



Mean yield 


per acre o 


f . 


Barley Oats 


Rye 


Wheat 


38 41 


14 


23 


21 26.8 


9 


16.1 


12.5 19 


12 


9.3 



Washington 

California 21 

Kansas 



Expressing these differences in percentages, we get: 

Washington 100 100 100 100 

California 55.2 65.3 64.3 70 

Kansas 32.9 46.3 85.7 40.4 

As the soils in the three regions are notably fertile, 
and were in 1879 very close, on the average, to virgin 
conditions, the differences in yield can hardly be attrib- 
uted to differences in plant -food other than as influenced 
by soil moisture ; and as the quantity of rain which falls 
in Kansas during the growing season, April to Septem- 
ber, inclusive, is 11.5 to 16.8 inches, while that in 
Washington is only 8.4 to 13.5 inches, it appears plain 
that in some way the available moisture is more effective 
on the Pacific border than it is in the 97th meridian 
region. 

It would be of very great practical importance to 
understand fully the causes which permit so small an 
amount of rain as that of eastern Washington, falling, 
so much of it, before the growing season, to ensure the 



104 Irrigation and Drainage 

maturity of such large crops under so clear a sky and in 
spite of so long and continuous a period of drought, 
while in western Kansas 25 to 38 per cent more rain- 
fall, well distributed through the growing season, pro- 
duces less than one -half the yield per acre. The yield 
is certainly less than one- half, because the averages 
used for Kansas are to'o large for the western section 
of the state, whose rainfall has been brought into 
comparison. 

While we are a long way from possessing the need- 
ful data for the solution of this problem, some of the 
factors are evident enough, and may be stated here. In 
the first place, the rains of the sections of California and 
of Washington under consideration fall in the cooler 
portion of the year, when the air is more nearly 
saturated and when the wind velocities are small, 
while the sun is much of the time obscured b}^ clouds. 
All these conditions conspire to permit a large per 
cent of the water which falls upon the ground to 
enter it deeply, without being lost by evaporation, 
while a deep, retentive soil serves to prevent loss by 
drainage. 

In western Kansas, on the other hand, where the 
rain falls largely in the form of showers in the heated, 
sunny season of the year, and where the wind veloci- 
ties are high and the air extremely dry, it is plain that 
a much larger per cent of water falling as rain must 
be at once lost by evaporation from the surface of the 
soil, before it has had an opportunity to enter it deeply 
enough to be retained by soil mulches. 

In the second place, a frequent surface wetting of 



lATte Rainfalls not Equally Productive 105 

the soil, such as takes place in Kansas, tends strongly 
to hold the roots near to the surface, where with scanty 
mulches they are certain to suffer severely whenever a 
period of ten days without rain occurs ; and if, under 
these conditions, the plant is able to send new roots 
more deeply into the soil, they can find there but a 
scanty supply of moisture, because there have been no 
winter rains sufficient to produce percolation. Then, 
again, after such a ten -day drought, with the surface 
roots now become inactive through a dying off of the 
absorbing root -hairs, when the next rain does fall, 
unless it is a very heavy one, the major part of it will 
be lost by evaporation from the soil, in the case of 
crops like wheat, oats, rye and barley, long before the 
plants are able to put themselves in position to take 
full advantage of it. 

In California and eastern Washington, the case is 
radically different. There the water gets well into the 
soil before the crop is put upon the ground. Moisture 
enough is present to produce germination, and the 
roots develop at first near the surface, when there is 
ample moisture present ; but later, under the rainless 
conditions, it is quite likely that they advance more 
and more deeply into the ground as the moisture in 
the upper layers of the soil becomes too scanty, and 
thus day by day the effectiveness of the soil -mulch is 
increased, while the roots have only to advance so far 
as is needful to allow capillarity to bring them the 
water they need from the store which the soil has re- 
tained. With these physical principles and conditions 
set down as foot -lights to illuminate our problem, and 



106 Irrigation and Drainage 

with the other fact for a side-light turned upon it, 
that 6 inches of water, when the crop can have it to 
use to the best advantage, is enough to produce 20 
bushels of wheat to the acre, we can see its outlines 
with sufficient clearness to feel sure that more study 
in the field would give us its full solution. As the 
matter now stands, the case is sufficiently clear that 
we may not conclude, because 9 to 12 inches of rain 
in California has produced abundant crops of wheat, 
that a similar rainfall in the sub -humid belt ought 
to produce like results. It should be sufficiently 
evident, also, that even with the best modes of till- 
age we can hope to adopt, there will still be much 
more water required per pound of dry matter pro- 
duced all through the sub -humid region, than is de- 
manded under the conditions of the lower San Joa- 
quin valley. 

The same principles make it very clear, also, that a 
judicious application of water by the methods of irri- 
gation, in many humid climates, is certain to be at- 
tended by marked increase in the yield. 



FREQUENCY AND LENGTH OF PERIODS OP 
DROUGHT 

In humid and sub-humid regions, it is the frequent recur- 
rence of periods of small or no rainfall, especially if they occur 
at the time when the crop is approaching or has reached the 
fruiting stage, that, more than anything else, makes extremely 
careful and thorough tillage, or else supplementary irrigation, 
indispensable, if large yields are to be realized. 

In cur repeated trials in the field cylinders here in Wiscon- 



Freqiiency and Length of Drought 107 

sin, we have found it necessary to water all of the crops grown 
in them as often as once in seven days; and even this period has 
been found too long for the soils which are coarse and sandy. 
So, too, in our field irrigation we have found that as much as 2 
inches of water may be applied to corn, cabbages and potatoes as 
often as once in 10 days, with decided advantage unless, in the 
interval, there has been a rain of from .5 to a full inch, falling 
nearly at one time, so as to penetrate the ground deeply. To 
what extent and to what advantage tillage may take the place of 
irrigation, or make it undesirable, we shall discuss in the next 
chapter. Starting with the soil well supplied with moisture at 
seeding time, and then a uniform distribution of rains equal to 1 
inch once in seven days through the growing season, we shall have 
all the moisture that would be needed for very large crops. On 
the average of years most parts of the United States east of the 
97th meridian have this amount of rain during the growing season. 
It is true, however, that in many parts of the humid districts the 
distribution of the rainfall in time and in quantity is such as to 
cause severe suffering from drought. 

To show just why it is that in Wisconsin the irrigation of 
ordinary farm crops does produce a very marked increase in the 
yield, we have made a study of the distribution of the rainfall at 
Madison for the years 1887 to 1897, inclusive. The results 
are here given in a condensed form, as an illustration of the type 
of rainfall conditions under which, in a humid climate, it may be 
desirable to irrigate where water privileges are such as to permit 
it to be done cheaply. 

It is generally true that a rain of .05 or even of .1 of an 
inch, ■ when it comes alone, separated by two or three days 
from any other rain, benefits ordinary farm crops but little ; but 
in order that we shall not undervalue the rain which falls, we 
have included everything, large and small alike, and have con- 
structed a table for these years, 1887 to 1897, which shows the 
length and number of periods in each year between April 1 and 
September 30, when there were consecutive days having a rain- 
fall whose sum did not exceed .05, .1, .5, 1, 1.5, 2, and 2.5 
inches. The table is given below : 



108 



Irrigation and Drainage 



Table showing the number of periods, and the mean length of these periods, in each 
year ivhen the amount of rain is not greater than that given at the head of the 
respective columns 

Rainfall Rainfall Rainfall Rainfall Rainfall Rainfall Rainfall 
of .05 in. of .1 in. of .5 in. of 1 in. of 1.5 in. of 2 in. of 2.5 in. 



O ™ 



o 



° p. 



1887 

1888 

1889 

1890 

1891 

1892 

1893 

1894 

1895 

1896 

1897 

Av. I'g'h 
period 

Av. No. 
periods 23.27 



20 
27 
21 

28 
20 
22 
22 

20 
21 

27 
28 



to 

.2 % 
^>' 
^^ 

«M «^ 
01 

d 

;^ 

22 

25 
20 
23 
20 
25 
23 
18 
23 
27 
28 



|1 
° p. 



5.82 



P-^ 



7 
6 
8 
5 
6 
7 
7 
5 
5 

6.18 



16 
20 
15 
22 
20 
16 
13 
27 
19 



4? o 

^ .in 
O P. 

d.£3 

a » 



TS u 



p'-d 



-0.2 



>t3 U 



" P. 

d.ia 



« .S! 5 



ft.ra 



-0.2 



^ ;? 



CO 

.2 ® 
d 



11 

8 
12 
7 
9 
9 
14 
6 



15 
13 
17 
11 
20 
18 
15 
9 
26 
15 



12 11 15 



9.27 



15 
10 
15 

9 

9 
12 
20 

7 
13 

12.27 



10 
16 

8 
19 
14 
13 

5 

19 
11 



18 
10 

9 
13 
14 

37 
10 
17 



16. 2-; 



23.09 



18.91 



15.55 



12.45 



7 
14 

7 
15 
12 

9 

5 
15 

8 



10 



H 

'C.2 
° p. 

d.r] 
Iz ^ 



CO 

d 



18 9 12 13 11 14 10 18 



8 21 



26 
13 
26 
12 
15 
14 
39 
12 
23 

19.91 



6 
6 

12 
5 

13 

10 
9 
4 

11 
6 



w 

-0.2 

^1 

6 si 

oi.ld 

24 
31 
31 
15 
36 
15 
18 
20 
44 
17 
31 . 

25.63 



8.17 



Studying this table, it will be seen that during the eleven 
years there have been on the average in the growing season 23 
periods of 5.82 days' duration when the rainfall has not exceeded 
.05 inches ; there have been 23 periods 6 days long, with a rain- 
fall of .1 inch ; 19 periods on the average 9 days long, with a 
rainfall of .5 inch ; 15 periods each year 12 days long, with 1 
inch ; 12 periods 16 days each, with but 1.5 inches ; 10 periods 
each season 19 days long, with 2 inches, and 8 periods each 
season of 25 days each, when the mean rainfall did not exceed 
2.5 inches. 

If we will now compare the field yields which are produced 
under these conditions of rainfall, we shall be better able to see 
how important are the quantity and time distribution of rain. It 



Frequency and Length of Drought 109 

is unfortunate that we are unable to present closely comparable 
data for more than the years 1894, '95, '96 and '97, and even for 
these years only for corn. As for other crops in the different 
years, they were grown on different soils ; but bringing the yields 
of dry matter of maize per acre into comparison with the rainfall 
conditions under which they were produced, we shall have the 
table which follows : 

Table showing the relation of yields of dry matter per acre to the quantity and 

distribution of rainfall 









Yield of dry 
matter per acre Aggregate No 


of inches of rainfall 


Year 


Periods 


TONS 


.05 


.1 


.5 


1 


1.5 


2 


2.5 


1894 


r No. of rainfall periods 
L Length days 


20 

7 


18 

7 


16 
9 


15 
12 


13 

14 


9 
14 


9 

20 


1895 


fNo. of 
I Length 




.. • .. 1.401 


21 
6 


23 

7 


13 
14 


9 

20 


5 

37 


5 
39 


4 
44 


1896 


/No. of 
\ Length 




.. .. 4.145 


27 
4 


27 
5 


27 
6 


26 

7 


19 
10 


15 
12 


11 

17 


1897 


/ No. of 
\ Length 




.. w 3.405 


28 
5 


28 
5 


19 
9 


15 
13 


11 
17 


8 
23 


6 

31 



If the rainfall in 1896 and in 1894 is compared with that in 
1895, when there was a very much smaller crop, it will be seen 
that the number of rainfall periods in 1895 is decidedly less, while 
the length of them is much greater. It was this much longer 
interval of time intervening between like quantities of rain which 
determined the small yield ; and it is this character of the rain 
of humid climates which so seriously cuts down the average 
yields per acre, and which makes it possible for the methods of 
irrigation to give such constant and such large yields wherever it 
is well practiced in arid climates. 

Taking the best year of the four, 1896, it will be seen that 
the average length of periods of 1 inch of rainfall was 7 days, 
and there were 26 of them in the six months, making about as 
uniform distribution of rain as is likely to occur in humid cli- 
mates ; but there were in this season 1 period of 10 days, 3 
periods of 11 days, 2 periods of 12 days and 2 periods of 13 days' 
duration with but 1 inch of rain, which are too long in Wisconsin 



110 



Irrigation and Drainage 



to permit the largest crops the soil is capable of carrying. This 
statement is founded upon the fact that with plenty of water the 
same soils did produce much larger crops, the differences being 
such as are given in the table below: 



Table showing differences in yield when the natural rainfall in Wisconsin is 
supplemented by irrigation 



Corn 



Yields per acre 

Potatoes Strawberries Cabbage 



Barley 



Clover 



^ i^ 



TONS TONS BU. BU. BOXES BOXES TONS TONS BU. 

1894 5.176 3.835 6,867 3,496 

1895 5.293 1.384 8,732 1,030 51 25 

1896 5.15 4.145 394.2 290.5 22.79 20.04 



BU. TONS TONS 



4.01 1.45 
3.632 2.254 



1897 4.252 3.405 333.9 212.3 



45.67 44.25 4.434 2.482 



These figures show very clearly the insufficiency of rain in 
these four years to produce the largest possible yields, and they 
show to what extent irrigation in a climate such as that which 
has occurred during the years 1894 to 1897 in Wisconsin is likely 
to increase the average yields. 



CONDITIONS WHICH MODIFY THE EFFECTIVENESS OP 

RAINFALL 

The rains which fall upon a given area are not equally effec- 
tive under all conditions of soil and topography, and hence it 
happens that irrigation may be desirable in localities where the 
amount of rain which falls may be both large and uniformly dis- 
tributed throughout the growing season. It has been pointed out, 
in the study aiming to measure the amount of water required to 
produce a pound of dry matter, that it was necessary to water the 
sandy soils of coarse texture once in three to four days in order 



m 



Conditions Modifying Effectiveness of Rainfall 111 

to prevent the crops from suffering for lack of moisture, while 
once in seven days met the needs of plants growing upon soils 
of the finer texture used in the experiments. 

The diflfieulty in the case of soils of coarse texture is, not 
that the water evaporates more rapidly from the surface of them, 
nor is it because more water must be present in them in order 
that plants may utilize it, for it is true that the surface evapora- 
tion from them is slower than with most other soils, and that 
plants may use the water more closely from them than is 
possible when the grains are smaller. The real trouble is found 
in the fact that when they are underlaid by a coarse subsoil, and 
when standing water in the ground is more than 5 feet below 
the surface, the water drains out so completely in a short time 
that not enough remains to keep the crop from wilting. 

We do not yet know how closely the water may be used up 
in field soils of different textures before crops of different kinds 
will begin to suffer, or will have their rate of growth checked ; 
but the writer has found that clover, timothy, blue -grass and 
maize have their growth brought nearly to a standstill in a clay 
loam soil underlaid with sand at 3 to 4 feet, when the amount of 
water left in it was that stated in the table below: 

Table showing the amount of water in a clay loam in the field when crops wilted 
and growth was brought nearly to a standstill 









Timothy and 








Clover 


Blue-grass 


Maize 


Depth of sample 


PER CENT 


PER CENT 


PER CENT 


0- 6 inches loam 


8.39 


6.55 


6.97 


6-12 


clay loam 


8.48 


7.62 


7.8 


12-18 ' 


clay- 


12.42 


11.49 


11.6 


18-24 ' 


clay 


13.27 


13.58 


11.98 


24-30 ' 


clay 


13.52 


13.26 


10.84 


40-43 ' 


' sand 


9.53 


18.37 


4.17 



Nothing more definite can be said regarding the data of this 
table, than that under the moisture relations there shown, growth 
was practically at a standstill, and that when very considerably 
larger percentages of water were present in the soil the normal 
rate of growth was checked. 



112 



Irrigation and Drainage 



How completely water will drain out of sands by percolation 
under conditions in which almost no evaporation can take place, is 
shown by the data in the table which follows, in which the results 
were obtained by a set of apparatus shown in Fig. 21. It will be 



— 6—1 r~0~T PV" 






Wm 

m 

m 







K'n'lv 



MM 

mi 





Fig. 21. Method of determining water-holding power of long columns of sand. 



seen that the conditions provided by the apparatus are such that 
standing water was maintained continuously in the soil at a level 
of 8 feet below the surface, and, hence, that the amount of water 
retained in the whole column was much greater than it would 
have been were it under such field conditions as when standing 



Water Lost hy Percolation 



113 



water in the ground is found at greater distances below the sur- 
face : 



Table showing the per cent of water in 8-foot columns of sand after percolation 
periods of different lengths 

Effective diameter of sand 
grains 474 mm. .185 mm. .155 mm. .1143 mm. .0826 mm. 



Height of sec'n 

above ground 

water 


INCHES F 


96 ... 


. 93 


93 ... 


. 90 


90 ... 


. 87 


87 ... 


. 84 


84 ... 


. 81 


81 ... 


. 78 


78 ... 


. 75 


75 ... 


. 72 


72 ... 


. 69 


69 ... 


. 66 


66 ... 


. 63 


63 ... 


. 60 


60 ... 


. 57 


57 ... 


. 54 


54 ... 


. 51 


51 ... 


. 48 


48 ... 


. 45 


45 ... 


. 42 


42 ... 


. 39 


39 ... 


. 36 


36 ... 


. 33 


33 ... 


. 30 


30 ... 


. 27 


27 ... 


. 24 


24 ... 


. 21 


21 ... 


. 18 


18 ... 


. 15 


15 ... 


. 12 


12 ... 


. 9 


9 ... 


. 6 


6 ... 


. 3 


3 ... 


. 



FEET 



Water retained after percolating over 2 years 



PER CENT 


PER CENT 


PER CENT 


PER CENT 


PER CENT 


.27 


.17 


.22 


1.26 


3.44 


.22 


.17 


.23 


1.16 


3.44 


.23 


.16 


.29 


1.34 


3.82 


.22 


.15 


.32 


1.61 


3.83 


.23 


.18 


.61 


1.98 


3.93 


.29 


.19 


1.07 


2.32 


4.19 


.44 


.26 


1.33 


2.61 


4.38 


.89 


.58 


1.57 


2.90 


4.92 


1.18 


1.16 


1.80 


3.12 


4.94 


1.48 


1.45 


1.85 


3.36 


5.70 


1.71 


1.67 


2.03 


3.56 


5.91 


1.80 


1.80 


2.18 


3.92 


6.43 


1.83 


1.86 


2.26 


4.22 


6.77 


1.93 


1.87 


2.27 


4.53 


7.72 


1.98 


1.98 


2.30 


4.88 


8.59 


2.02 


1.92 


2.38 


5.42 


9.42 


2.03 


2.12 


2.46 


6.03 


10.50 


2.02 


2.07 


2.71 


6.99 


11.34 


2.06 


2.18 


3.08 


7.47 


12.58 


2.17 


2.29 


3.46 


8.71 


13 


2.31 


2.48 


4.10 


10.54 


14.95 


2.36 


2.65 


5.09 


11.77 


15.90 


2.63 


3.14 


6.36 


12.95 


17.20 


2.86 


3.63 


8.74 


15.05 


17.96 


3.42 


4.71 


13.52 


17.24 


18.92 


4.26 


6.76 


23.57 


19.08 


20.49 


6.41 


9.38 


27.93 


19.37 


21.34 


9.77 


14.66 


23.61 


21.44 


21.63 


16.08 


21.31 


22.46 


22.69 


22.68 


19.33 


22.39 


22 76 


23.20 


23.39 


20.96 


2352 


22.88 


24.22 


30.28 


21.58 


24.61 


23.54 


25.07 


24.06 



H 



114 Irrigation and Drainage 



Total water retained — < 



2,121 4 


2,474.9 


3,515. 4,576.2 


5,831.5 


4.24 


5.05 


7.25 9.41 


11.82 


3,128. 


3,551.1 


4,259.9 5,672. 


6,659.7 


6.25 


7.238 


8.785 11.66 


13.5 


2,926. 


3,213.5 


4,094.7 5,416.2 


6,452.8 


5.846 


6.753 


8.445 11.13 


13.08 


L0,425.2 


10,356.2 


10,329.1 10,289.7 


10,606.8 


20.84 


21.12 


21.3 21.15 


21.5 



fgms. 
per cent 

Water retained after 4J'gms. 
days I per cent 

Water retained after 9/gms. 
days I per cent 

Total water recovered. ..\ ' . 

L per cent 

Totalweightof dry sand... gms. 50,050. 49,060. 48.490. 48,650. 49,340. 

A glance at this table shows how completely and how rapidly 
water will drain away by downward percolation from the coarse 
and fine sauds when there is nothing within 8 feet of the surface 
to prevent it. It will be seen that in four days the coarsest sand 
had lost nearly three-quarters of all the water it could contain 
under flooded conditions, while the finest had lost nearly one- 
half ; and this has occurred, too, under such conditions that 
standing water is maintained within 8 feet of the surface. Had 
standing water been 16 feet from the surface, it is quite likely 
that the surface 8 feet of these sands would not have retained 3 
per cent in the coarsest sample nor 5 per cent in the finest. 

With such a rate of loss of water from sands as this, it must 
be plain that the coarser soils, when they are long distances from 
standing water in the ground, or are not underlaid with a more 
impervious stratum near the surface, must lose the water which 
falls upon them as rain so rapidly that even in very humid regions 
they cannot maintain profitable crops without irrigation. 

It is this fact of coarse texture, coupled with the long inter- 
vals of deficient rain, more than a lack of plant-food, which has 
maintained in an unproductive state the extensive areas of sandy 
lands found in Minnesota, Wisconsin, Michigan, New York, New 
Jersey, and further south, in the United states, and throughout 
Belgium, Holland, and the plains of northern Germany, in 
Europe. Had the soils of these areas identically the same 
chemical composition, but a texture as fine as that of our best 
soils, so that water would drain from them no more rapidly, 
profitable agriculture could be practiced upon them under the 
rainfall conditions which exist. And it is possible to so supple- 



Water Lost hy Surface Drainage 115 

ment the rainfall upon these types of land by irrigation as, even 
with the coarse texture they have, to make them bear remuner- 
ative crops of various kinds, as has been abundantly proved in 
many places. 

Passing from the extreme type of "barrens" soil which we 
have been discussing, there are extremely large areas of only the 
less coarse loamy sands and sandy loams in all humid climates, 
where supplementary irrigation, could it be practiced, would 
greatly increase the average yields beyond the largest which are 
possible with the best of tillage ; but the truth of this proposition 
does not carry with it the corollary that it will pay to irrigate 
them whenever there is an abundance of water to do so. 

Then, there are topographic conditions which greatly diminish 
the effectiveness of the rain which may fall in a given locality. 
When the fields are decidedly rolling, every one is familiar with 
the fact that wherever heavy rains occur in short periods of time 
very considerable percentages of such rains flow at once over the 
surface to the lower lying lands, producing only damaging effects 
upon the hillsides. Under such conditions, it is plain that the 
measured rainfall of the growing season is not available for crop 
production, even though the texture of the soil were such as to 
retain the whole of it, could it rest upon the surface long enough 
to be absorbed. Further than this, the brows of hills, where 
they are exposed to the prevailing winds, lose a much higher 
percentage of the absorbed soil moisture by surface evaporation than 
is the case on the level plains or in the sheltered valleys, and 
from this it follows that when the whole rainfall of the growing 
season is only enough to make the soil produce at its full 
capacity, the exposed hillsides must receive irrigation sufficient 
to make good the losses by surface drainage and greater evapo- 
ration, if equally large yields per acre are expected. 

Again, in rolling countries, where the higher lands are 
porous, the rains which are there lost by deep percolation reap- 
pear under the lower lands, to supplement the rain which falls 
directly there, and often to such an extent as to make under- 
draining a necessity. Where these conditions exist, and where 
drainage is sufficient, so that crops may take advantage of the 



116 Irrigation and Drainage 

underflow which gives rise to a natural sub -irrigation, it is evi- 
dent that on such lands a much smaller rainfall, and even longer 
intervals between rains, may occur without producing suffering 
from drought. 

From what has been shown regarding the amount of water 
used by different crops in coming to maturity, it is plain that 
with a full command of water for irrigation, it would be possible 
for crops to be grown on a given soil in a given locality when the 
natural rainfall would not permit that crop to be so grown. It 
is plain, therefore, that neither the amount of rain nor the dis- 
tribution of it are sufficient to determine under what conditions 
irrigation will or will not pay. 



1 



CHAPTER III 

THE EXTENT TO WHICH TILLAGE MAY TAKE THE 
PLACE OF BAIN OR IRRIGATION 

Were it desirable to irrigate all agricultural lands 
lying in humid climates, it would not be possible to 
do so, on account of the insufficiency of water for the 
purpose. The truth of this proposition will be evident 
if we deal quantitatively with the problem. 

THE INSUFFICIENCY OF WATER TO IRRIGATE ALL 
CULTIVATED LANDS 

Humphreys and Abbott have placed the mean an- 
nual discharge of the Mississippi at 19,500,000,000,000 
cubic feet, while the catchment area is placed at 1,- 
244,000 square miles. Assuming that these quantities 
are correct, then the mean annual run -off for the 
whole Mississippi basin would be 6.747 inches. But 
not all this run -off is available for irrigation, were it 
desirable to so use it ; for during a large part of the 
time this water is flowing away when the season does 
not permit of its being used, and it is impracticable to 
impound it and hold it until it might be used. If we 
take the mean daily discharge of the river as -wir of 
its annual amount, and allow that the whole of this is 

(117) 



118 Irrigation mid Drainage 

available for irrigation purposes during the irrigation 
season, it is capable of watering but .092 of the catch- 
ment area at the rate of 2 inches of water once m 10 
days. 

It is true that the mean run -off for the whole 
basin is less than is found in much of the United 
States ; but, taking a district where the mean drainage 
to the sea is 30 inches instead of 6.7, and supposing 
that this is collected into canals, so as to be used for 
irrigation, then it would be able to supply only about 
A of the area at the rate assumed above. It is 
safe to say that these estimates of the area which 
might be irrigated with such amounts of water is too 
large, for the summer discharge, when irrigation is 
needed, is in most drainage basins much less than 
the mean values which have been taken in making 
the calculations. 

Newell has made as close an estimate of the mean 
annual run -off for the United States as the then ex- 
isting data would permit, and has expressed the 
results in a map, which is reproduced in Fig. 22. An 
inspection of this map will make it plain, in connec- 
tion with what has been said, that however great irri- 
gation developments may become in the future, it is 
not possible for the practice to be extended so as to 
displace the methods of "dry farming." Hence the 
question. How far may tillage compensate for a defi- 
cient rainfall ? will long remain a pertinent one in 
agricultural practice. 

Since much less than one -half of agricultural lands 
can be irrigated under any efforts which can be made, 



120 Irrigation and Drainage 

it is plain that the question, What are the largest 
possible yields which may be realized without irri- 
gation ? is of much greater practical moment than its 
converse. 

THE MOST WHICH MAY BE HOPED FOR TILLAGE 
IN THE USE OF WATER 

We have, as yet, been unable experimentally to 
demonstrate that any method of handling the soil 
under field conditions will permit it to abstract from 
the air above it an amount of moisture sufficiently 
large to materially contribute to the supply already in 
the soil, and thus aid in compensating for a deficient 
rainfall. The discussion presented on a preceding 
page, regarding the production of wheat in California 
and Washington without irrigation, certainly lends no 
weight to the view that the hygroscopic power of soils 
aids in supplying moisture to the crops under field 
conditions. Still, it must be admitted that those who 
maintain that soils do absorb important quantities of 
moisture from the air direct may continue to do so 
without fear of successful refutation by existing posi- 
tive knowledge. 

If it is true that soils do not withdraw from the 
air important quantities of water, then the most which 
can be hoped for by methods of tillage is that they 
may store in the soil and retain there the water which 
falls as rain, until that shall be removed by the action 
of the roots of the crop growing upon the field. Cer- 
tain it is that no method of tillage now practiced can 



Amount of Bain Needed 121 

very much increase the moisture in the soil above that 
which falls as rain or snow. 

Further than this, we have no reason to believe 
that mere tillage, as such, can in any way diminish 
the rate of transpiration from the crop which is grow- 
ing upon the soil being tilled, unless, indeed, it should 
be done by root -pruning, a method decidedly injurious 
in most cases. It follows, therefore, that in no way 
can we hope, by methods of tillage, to diminish the 
loss of water by transpiration through the crop itself. 
We may, indeed, make the conditions for growth so 
favorable that the maximum amount of dry matter is 
developed during the time a given amount of water 
is being evaporated from the surface of the crop ; but 
so far as the direct influence of tillage is concerned, it 
can only lessen the evaporation from the soil surface, 
and reduce the losses by percolation and by surface 
drainage. No amount or kind of tillage can dispense 
with water ; that must be had, either from rain or 
snow, or be supplied by irrigation. With water enough 
in the soil to make a crop, good tillage will bring the 
most out of it ; but when the rainfall has really been 
deficient, nothing short of irrigation can make the crop. 



AMOUNT OF RAIN NEEDED TO PRODUCE CROPS 
IN HUMID AND SUB -HUMID REGIONS 

Having pointed out in a general way the limitations of tillage 
in conserving soil moisture for crop production, it is important to 
show how great its possibilittes may be when unaided by irriga- 
tion ; for if in humid and sub -humid climates tillage may enable 



122 Irrigation and Drainage 

all soils to produce maximum crops of all kinds, then irrigation 
will be unnecessary in them. 

It has been shown that, under conditions in which no water 
can be lost by surface or under- drainage: 

Clover uses 5.089 acre-inches in producing one ton of dry matter. 
Oats " 4.447 

Barley " 4.096 
Maize " 2.391 
Potatoes use 3.399 

These figures are an approximate measure of the demands of 
those crops for water, and if one, twc or three tons of dry matter 
per acre are to be produced by these crops, then the amount of 
available rainfall needed will be given by multiplying the figures 
in this table by the yield which is expected per acre from 
the soil. 

Let us see what the available rainfall is in various parts of 
the eastern and central United States. To make the discussion as 
pointed as possible, let us draw our data from the states of Illi- 
nois, Indiana, Iowa, eastern Kansas, Maine, Michigan, Missouri, 
Minnesota, New York, Ohio, Pennsylvania, Vermont, and Wiscon- 
sin. In these states, what is the amount of rainfall available for 
crop production ? 

In the map. Fig. 23, is represented the mean annual rainfall of 
the United States, as given by the Weather Bureau. Such a map, 
however, does not show the amount of water which is available for 
crop production, because, as shown on the map, Fig. 22, a large 
part of this rain is carried to the sea in the rivers, and cannot, 
therefore, be used in producing crops. But if the rains which 
would drain away were subtracted from the mean annual rainfall, 
the difference would still be too large, for we have many showers 
which are too slight to be of any service whatever. Not only this, 
but very light rains often do positive injury by destroying the 
effectiveness of earth mulches which have been developed by till- 
age, thus causing a loss of a part of the water already in the soil, 
with that which fell as rain. 

It is further necessary, in discussing this problem, to consider 




_/ 






> 



pa 
o 




124 Irrigation and Drainage 

the growing season of the specific crop in question, in order to 
know whether tillage alone will answer for that crop, unaided by 
irrigation. The first crop of clover, for example, must be largely- 
made by the rains of May and June in the states which have been 
named, while the crop of potatoes will be determined more largely 
by that which falls between June and October. The period of 
barley would extend from May 1 nearly through July ; oats, from 
May to the middle of August ; and maize, from the middle of May 
to the middle of September. 

In the table which follows, the amount of rain which falls 
during the growing season of barley, oats and maize has been 
given, and from the averages have been deducted the am-ounts 
which it is quite certain do not become available for crop produc- 
tion, on account of loss by drainage and by the light rains not 
penetrating deeply enough to be of service agriculturally: 

Table showing the mean rainfall for the growing season for barley, oats 

and maize Rainfall in inches for 
Barley 

^linois 13 

Indiana 13.5 

Iowa 12.5 

Eastern Kansas 12 

Southern Maine 10.5 

Southern Michigan 9.5 

Missoiiri 13.25 

Minnesota 10.75 

New York 10.25 

Ohio 11.75 

Pennsylvania 12 

Vermont 10.5 

Wisconsin 11.5 



Oats 


Maize 


15 


15.25 


15.25 


16.25 


14.25 


15.375 


13.625 


14.5 


12.25 


14 


11 


12.625 


15 


16.375 


12.25 


13.75 


12 


13.5 


13.5 


15 


14 


15.75 


12.5 


14.75 


13.25 


15 


13.375 


14.779 


3.185 


2.765 


10.19 


12.014 



Mean 11.616 

Estimated loss by percolation and from light showers. 2.964 

Mean effective rain 8.625 

In estimating the loss from percolation and small showers, 2 
inches has been assumed as the amount of percolation in the ease 
of barley and oats, and 1.5 inches for maize. The amount deducted 
for small, ineffective showers has been gotten by taking the total 



Tmie Distributio7i of Bain 125 

rainfall for Madison, Wisconsin, from 1887 to 18©7, which was 
less than .2 of an inch in any day of 24 hours during the periods 
covered by the table. 

Now, these amounts of effective rain, could they be used with 
the same economy as we were able to use them in our plant cylin- 
ders, ought to produce the following yields per acre: 

Bu. per acre 

Barley 40.29 

Oats 64.97 

Maize 71.51 

In making these calculations, the ratio of grain to straw for 
barley has been taken as 2 to 3, and for oats as 1 to 1.448: and 
we have used the percentages of water in grain and straw given in 
tables of feeding -stuffs. In the case of maize, data derived from 
direct determinations by the writer have been used. 

It will be seen that these computed yields, although much 
larger than average yields, are, nevertheless, very close to what is 
expected during our best seasons, when there has been plenty of 
rain, well distributed, and when the crop has not been affected by 
disease or insects. It appears, therefore, that the rainfall for the 
thirteen states enumerated is sufficient in quantity to produce very 
heavy crops, not only of the three grains named, but of many 
others also. 



THE DISTRIBUTION OF KAIN IN TIME USUALLY UNFA- 
VORABLE TO MAXIMUM YIELDS 

There is little question that in the thirteeen states named, the 
mean yields of barley, oats and maize would easily be held to 
41, 64 and 75 bushels per acre respectively, if it were only possible 
to control the distribution of rain in time and in quantity, as it is 
controlled by irrigation. As it is, however, such large mean 
yields can never be reached by tillage alone in a territory as 
extended as that under consideration. This will be evident from 
the table which follows, in which the mean yields of barley, oat§ 



126 Irrigation and Drainage 

and maize for 1879 are given as reported for the 10th Census for 

the thirteen states: 

Bu. barley Bu. oats Bu. maize 

per acre per acre per acre 

Illinois 22.25 32.24 36.12 

Indiana 23.35 25.02 31.39 

Iowa 20.23 33.57 41.57 

Kansas 12.52 18.77 30.93 

Maine 21.81 28.76 30.99 

Michigan 22.1 33.93 35.3 

Missouri 19.01 21.34 36.22 

Minnesota 25.62 37.97 33.81 

New York 21.85 29.79 32.97 

Ohio 29.7 31.49 34.09 

Pennsylvania 18.57 27.34 33.37 

Vermont 25.36 37.57 36.46 

Wisconsin 24.68 34.43 33.71 

Mean 22.08 30.17 34.38 

If a comparison is made between these reported yields and 
those which are given above as possible with the recorded rain- 
falls, when a favorable distribution in time occurs, it will be seen 
that the mean reported yields are only about half as large as the 
computed ones, and as observed ones are in localities where the 
distribution of rain in time and in quantity has been favorable. 

These small average yields, reported from so many states, 
and agreeing' so closely one with another, must be looked upon 
as expressing conditions unfavorable to large 'yields, and condi- 
tions which the best of management cannot hope wholly to 
counteract. 

The facts are that we are here confronted with results which 
are due, in a very large measure, to the long intervals between 
effective rains, to which reference has already been made. This 
uneven distribution is so general in its character that when 
the yields over wide areas are brought together for comparison, 
the small yields due to faulty distribution of rain so far outweigh 
the large yields, where the amount of moisture has been just 
right, that small averages are inevitable. Nor is this condition 
of things strange ; for, since the rainfall is in no way controlled 
by any factor operating to cause precipitation, either when it is 



Tillage to Conserve Moisture 127 

wanted or in the amount which the particular crop on the par- 
ticular soil may at that time need, it cannot be expected that 
such a regime of chance would on the average develop the con- 
ditions most favorable to large crops. 



THE METHODS OF TILLAGE TO CONSERVE MOISTURE 
ARE OFTEN INAPPLICABLE 

If it is urged that better tillage and more systematic rota- 
tions of crops, coupled with a more rational practice of fertiliza- 
tion of the soil, would go a long way toward making larger 
average yields, every one must admit the truth of the assertion. 
But, while this is true, it must still be recognized that there are 
some cases in which the methods of tillage to conserve soil mois- 
ture are either wholly inapplicable or they may be applied only 
with so great difficulty or with so small an effect, that they have 
never come into general use for the specific purpose of saving 
soil moisture. 

The most important illustration in point is that of the hay 
crop, with which should also be associated that of pasture as 
well, when these are made from the grasses and from clover. 
With these two crops, hay and pasture, which together cover a 
wider acreage than any other single crop grown, there has not 
been and cannot well be any method of tillage aiming specifically 
to conserve soil moisture for the use of the crop. 

In the thirteen states referred to when discussing the yields 
of barley, oats and maize, there were cut 24,439,485 acres of 
grass, making 28,314,650 tons of hay, or at the mean rate of 
1.158 tons per acre, in 1879. Nearly all of this hay is made 
during the months of May and June, when there is a mean rain- 
fall for the thirteen states amounting to 7.83 inches, of which 
not less than 2 inches is lost by percolation, and nearly .69 of an 
inch is ineffective on account of showers giving less than .2 of 
an inch, thus leaving an effective rain of 5.14 inches 

It has been shown that clover uses 5.089 acre -inches of water 
in producing one ton of dry matter, and at this rate 5.14 inches 



128 Irrigation and Drainage 

of effective rain ought to give a yield of 1.01 tons of dry matter, 
equal to 1.188 tons of hay containing 15 per cent of water, while 
the observed mean yield is 1.158 tons. Now, this yield of 1.1 
tons per acre is not what a farmer calls a good yield, for 1.5 
tons to 2 tons per acre of hay are often cut ; but these larger 
yields are invariably associated with seasons of early heavy rain- 
fall. It must be evident, then, that in the thirteen states from 
Maine to eastern Kansas there are large areas where, if water 
could be applied to the first crop of hay, the yield might easily 
be increased 40 to 90 per cent, and there can be no question 
that the aggregate extent of such areas exceeds what could be 
supplied by all the water of all the rivers and all the ground 
water of those states. 

Then, again, in the case of such crops as wheat, oats, barley, 
rye, buckwheat, and the millets, which are sown broadcast or in 
close drills, it has not been usual to practice methods of tillage 
aiming specifically to save moisture ; but when the acreage of 
these crops in the United States, together with that of hay and 
pasture, is set aside, there remains relatively but a small part 
of the cultivated lands upon which intertillage is or can well be 
practiced. 

These statements are made neither to depreciate the impor- 
tance of conserving soil moisture by tillage nor to emphasize the 
importance of irrigation, but rather that each may be seen in its 
true perspective ; for the fact is, neither method is universally 
adapted to meet the needs of insufficient rain at all times and in 
all places. But there are conditions for which each is better 
suited than the other, and for a man to know these is to make 
him a better farmer. 

TILLAGE TO CONSERVE SOIL MOISTURE IS CHIEFLY 

EFFECTIVE IN SAVING THE WINTER AND 

EARLY SPRING RAINS 

It is not sufficiently appreciated that early and frequent till- 
age where irrigation is not practiced is far more important and 
effective in conserving soil moisture than later tillage can be 
after the ground once becomes dry. From this it follows that 



1 



Tillage to Conserve Moisture 129 

intertillage and surface tillage generally can be counted upon as 
capable of saving to the crop which is to be grown upon the 
ground only a part of the rains which fall in winter and spring. 
The rains of later June and July, August and September are 
usually beyond the power of tillage to conserve in any marked 
degree, without at the same time seriously injuring the roots of 
vegetation growing upon the ground. 

In the first place, after the last of June, in climates like 
that of the thirteen states selected, the water of nearly all rains 
is absorbed and retained in the surface 3 inches of soil or less. 
It is only the rains exceeding 1 inch which penetrate more deeply 
than this ; and to stir a wet soil is to hasten the rate of evapora- 
tion of moisture from the soil stirred. If, then, the roots of a 
crop have dried the surface 8 inches of soil so that it contains 
but 20 to 30 per cent of its full amount, and a rain falls which 
wets in but 2 inches, stirring that soil can save but little of the 
moisture. Further than this, when the surface of the soil has 
become so dry, capillarity acts very slowly to conduct the water 
downward into the soil. 

In the second place, most cultivated crops, in order to take 
advantage of the general fact that summer rains do not as a rule 
penetrate deeply into the soil, develop a system of roots ex- 
tremely close to the surface of the ground, where momentary ad- 
vantage may be taken of those rains which do not wet in deeply ; 
and hence it is that in sub-humid climates, and after a dry time 
in all climates, surface cultivation right after a rain may do posi- 
tive injury by cutting off roots which have been developed to 
take advantage of such rains, while at the same time the rate 
of evaporation from the stirred soil has been increased. Here, 
again, it is seen that rigid physical laws and conditions have set 
limitations to the methods of tillage as a substitute for irrigation. 

MIDSUMMER AND EARLY FALL CROPS DIFFICULT TO 
GROW WITHOUT IRRIGATION 

The fact that after early summer the surface of the ground 
usually becomes quite dry, coupled with the other fact that water 



130 Irrigation and Drainage 

percolates and travels downward through such soil with difl&eulty, 
makes the growing of a second crop of almost any kind very 
diflcult and uncertain by methods of tillage unaided by irriga- 
tion. Every one is familiar with the fact of short pastures in 
midsummer and early fall, and that secoud crops of hay can be 
raised only in exceptional seasons, and even then they are seldom 
heavy. 

The difficulty in these cases is not that less rain falls during 
the summer and autumn, for the measured amount is actually 
greater. Neither is it true that they will not grow because it is 
out of season, for when plenty of water is supplied heavy crops 
of grass are obtained for the second cutting. As a matter of 
fact, the summer rains are less effective because they are re- 
tained so near to the surface as not to come within reach of the 
roots before they are lost by surface evaporation. 

In our own experiments in irrigating clover, there has been 
secured for the second crop of clover hay 1.789 tons in 1895, 
2.035. tons in 1896, and 1.648 tons of hay, containing 15 per cent 
of water, in 1897, or an average for three years of 1.824 tons per 
acre. When it is recalled that the average yield of hay per acre 
for the thirteen states cited is but little more than 1 ton per acre 
for the first crop, when the rains have their maximum effective- 
ness, it is plain that without irrigation it is not possible to grow 
a paying second crop of hay to any extent in either the sub- 
humid or humid parts of the United States. Further than this, 
on account of the small effectiveness of summer rains, it is often 
quite impossible to secure a catch of clover with any of the small 
grains, while with irrigation the catch would be positively as- 
sured every year. These are cases in which present methods of 
tillage can do nothing, but in which irrigation will give certain 
results. 

The present season we put into the silo 6,552 pounds of 
clover and volunteer barley, cut from .58 acres of ground upon 
which had been harvested 45 bushels of barley to the acre. This 
was rendered possible by irrigating the land, and thus forcing 
the new seeding of clover after the crop was removed. In this 
way it was possible to get two good crops in one season from the 



Fall Plowing to Conserve Moisture 131 

same piece of ground ; namely, 45 bushels of barley per acre, 
and the equivalent of 1.4 tons of hay containing 15 per cent of 
water. Only very extraordinary seasons would by any method 
of tillage permit this to be done. 



MEANS OP CONSERVING MOISTURE 

1. Fall Plotving to Conserve Moisture 

In those parts of the world where winter precipita- 
tion is not large, so as to over -saturate the soil, and 
so as to cause the running together of soils, and thus 
destroy their tilth, fall plowing may be found very 
desirable when its chief object is to diminish surface 
evaporation during the winter and early spring, and 
where it is desirable to facilitate the ready and deeper 
penetration of the water into the soil which, during 
the growing season, has become dried to considerable 
depths. 

In order that fall plowing may be most effective in 
this way, it should be done as late as practicable, so 
that its looseness may not be destroyed by the early 
rains, and its usefulness as a mulch thus reduced; and 
also in order that it may allow the later rains and melt- 
ing snows to drop easily and more completely through 
it, when surface drainage will be prevented, and loss 
by evaporation will be reduced to the minimum. In 
such conditions capillarity and gravity may together 
aid in conveying the water into the second, third and 
fourth feet, where it will become most effective in 
supplementing the spring and early summer rains. 

The writer has shown, in "The Soil," p. 187, that 



132 Irrigation and Drainage 

land in Wisconsin fall -plowed late in the season was 
found in the spring, even as late as May 14, to con- 
tain not less than 6 pounds of water to the square 
foot more than similar adjacent land not so treated. 
This is equivalent to 1.15 inches of rain, a very 
important quantity to have been stored in the soil at 
so late a period and in such a position that inter- 
tillage is certain to retain it for service when it is 
needed. 

It will be readily appreciated that this sort of tillage 
to conserve moisture is most important in the sub- 
humid and humid climates, whenever those dry seasons 
occur which close the year with an under -supply of 
soil moisture. 

It should not be inferred that this sort of tillage to 
save moisture must be confined to such lands as are to 
be sowed to small grains in the spring, or even planted 
to corn or potatoes. It is particularly desirable in all 
lines of orcharding, and where small fruits and grapes 
are grown. The laying down and covering of the 
plants need not prevent it, for the plowing may imme- 
diately precede the laying down. In the growing of 
small fruits without irrigation, the late fall tillage, just 
before the ground freezes, is a matter of considerable 
moment, because with strawberries, raspberries and 
blackberries it very often happens that a shortage of 
soil moisture just at the fruiting season results in a 
very serious loss through a reduction of the yield, 
and late, deep tillage will usually lessen this danger. 
If it should be urged by some that this practice 
applied to orchards would tend to stimulate a too late 



Suhsoiling to Conserve Moisture 



133 



growth of wood in the fall, and thus lead to danger 
from winter -killing, the reply is that when it is done 
late, just before freezing up, there can be no danger 
on this score. 

2. Subsoiling to Conserve Moisture 

Subsoiling to conserve soil moisture cannot have 
the extended practice that methods of surface tillage 
should, but there are cases when it is quite likely to 
prove sufficiently helpful to pay for the relatively heavy 
expense which it involves. In view of this fact, and 
because it is being urged particularly in the sub-humid 











r-"FOOT 




:mm:m;Pi^-^^: 



^ 



pOIOn 



u 



^^:r.-\r. 



3" 



;V:::.V. ■*•■.• •:••■ 



4TM » ,, 



•. •G■AIN.ED:14.LB6• 



; ; . ;::LP:5T IS&;LB5^ 



51"" 



f■^f.■|;^p^■|^^■p^■>^i::?■^^t^;:i■t^^f::^^ 



Fig. 24. Method of determining the iniliienee of subsoiling. 

belt, the principles underlying the practice should be 
clearly understood. 

The method used to demonstrate the influence of 
subsoiling in retaining the rains which fall upon the 



134 Irrigation and Drainage 

ground is illustrated in Fig. 24, where all losses by 
surface evaporation were prevented by placing an air- 
tight cover over the areas under experiment. In order 
that the extreme influence of subsoiling might be 
ascertained, 8 inches of the surface soil was completely 
removed from an area 6x6 feet on a side, and when 
the subsoil had been spaded to a depth of 13 inches 
more it was returned to its place without firming in any 
way, except to smooth the surface with a plank pressed 
down by the weight of a man. After samples of soil 
had been taken from this and the adjacent area, to give 
the existing water content, water was slowly sprinkled 
over the two surfaces until 254.41 pounds, or 1.36 
inches, had been added to each, and then they were 
covered, as shown in the figure, and allowed to stand 
from June 11 until June 15, when the covers were 
removed and samples of soil again taken, to demon- 
strate what changes had occurred. 

When this was done it was found that the water 
added had effected the changes which are recorded in 
the table which follows : 



The first foot gained 

The second foot gained 

The third foot gained 

The fourth foot gained .... 
The fifth foot lost 

Total water gained 

Total water added 

Difference +14.24 —126.1 



Subsoiled 


Not STiTssoiled 


Difference 


LBS. 


LBS. 


LBS. 


124.6 


102.1 


+22.5 


72.57 


10.34 


+62.23 


38.22 


12.05 


+26.17 


33.26 


3.82 


+29.43 


2.29 


19.5 


—17.21 


268.65 


128.31 




254.41 


254.41 





Subsoiling to Conserve Moisture 135 

It will thus be seen that the subsoiled ground, 
under conditions where no evaporation could take place 
from the surface, had not only retained all the wat^r 
which had been added to it, but that it had actually 
gained by capillarity from the adjacent soil 14.24 
pounds additional. The ground not subsoiled, on the 
other hand, had actually lost, without evaporation from 
the surface of the soil, 126.1 pounds of water. 

In a second experiment, which was handled in the 
saime way, except that no water was added to the sur- 
face, the treated soil was allowed to stand from June 
26 to July 2, covered so that no evaporation could 
take place from the surface, the object being to learn 
whether capillary action would draw moisture from 
below into the subsoiled earth, and thus increase its 
water supply. The changes which took place are 
shown by the following figures : 

On Subsoiled Ground 
1st foot 2iid foot 3rd foot 4th foot 5th foot 

PER CENT PER CENT PER CENT PER CENT PER CENT 

June26{^^°\\*^/^^} 23.29 21.89 17.85 14.14 19.55 

July 2 {^t°cS} 22.66 22.50 17.49 14.45 20.27 

Change — .63 + .61 — .36 + .31 + .72 

On Ground not Subsoiled 

June 26— start.... 22.52 20.67 17.74 15.06 19.34 
July 2— close 23.97 22.09 18.92 14.62 18.38 

Change +1.45 +1.32 +1.18 —.44 —.96 

It appears from these results that there was but 



136 Irrigation and Drainage 

little tendency for the deeper soil water to pass npward 
by capillarity into the subsoiled earth. But quite the 
opposite was the case with the ground not subsoiled, 
for here the upper 3 feet had each gained more than 
1 per cent of their drj' weight of water. Express- 
ing the movement which had taken place during the 
6 days in pounds of water on the 36 square feet of 
surface, we find that the surface 3 feet had gained 
129.69 pounds, while the lower 2 feet had lost 53.52 
pounds, leaving an absolute gain of 76.17 pounds. In 
the case of the subsoiled ground, the surface 3 feet 
showed a loss of 11.14 pounds, and the lower 2 feet a 
gain of 39.38, making an absolute gain to the area of 
only 28.24 pounds. 

In another field trial, when a piece of land was 
subsoiled on October 22, while a strip on each side of 
this was plowed without subsoiling, the water in the 
soil was found in the spring to be distributed in the 
manner indicated below : 



First foot 

Second foot 

Third foot 

Fourth foot 

Total 69.10 68.76 -f . 34 

Here it will be seen that the surface foot of 
subsoiled ground contained nearly 2 pounds less 
water than that not subsoiled, but that the absolute 



Subsoiled 
in the field 


Not subsoiled 
in the field 


Difference 


LBS. 


LBS. 


LBS. 


15.47 


17.41 


—1.94 


17.61 


16.31 


+1.30 


18.19 


17.84 


+ .35 


17.83 


17.20 


+ .63 



Suhsoiling to Conserve Moisture 137 

amount of water in the two cases is practically the 
same. 

In a fourth experiment to show the effect of sub- 
soiling in the spring on the water content of the soil 
in the fall, one of the small areas already described was 
allowed to stand exposed from June until September, 
75 days, without in any way disturbing the surface, 
except to keep it free from weeds by shaving them off 
with a sharp hoe. The results were these : 



First foot . . . 
Second foot 
Third foot . . 
Fourth foot . 
Fifth foot . 



Here, again, the results have the same general char- 
acter as they did when the subsoil period was from 
October to April, the surface foot of subsoiled ground 
being the dryest, while the next 3 feet are more moist. 
When the effect of subsoiling in this case is expressed 
in inches of rain, the gain in the saving of soil moisture 
amounts to 1.64 inches, which is a very important 
amount. 

The effects of subsoiling probably do not last much 
longer than a single season, unless there has been but 
little rain, so that the ground has never been thoroughly 
saturated, permitting it to again settle together. In 
the case of the field trial here reported, samples of soil 
were taken on the same ground April 8, April 16, and 



Subsoiled 
ground 


Not subsoiled 
ground 


Difference 


PER CENT 


PER CENT 


PER CENT 


17.07 


18.91 


—1.84 


23.29 


19.42 


+3.87 


22.76 


17.78 


+4.98 


16.35 


14.19 


+2.16 


18.14 


19.20 


—1.06 



138 Irrigation and Drainage 

again May 5, in order to discover whether in that time 
progressive changes would take place. Between the 
first and last date there had been a total rainfall of 5.33 
inches, making conditions very favorable indeed to 
obliterate the effects of the subsoiling in a short time. 
The changes which these rains, together with the fitting 
and planting of the ground, produced, are shown in the 
table below: 

. April 8 . / April 16 

Not Not 

Subsoiled subsoiled Difference Subsoiled subsoiled Difference 

PER CENT PER CENT PER CENT PER CENT PER CENT PER CENT 

First ft 19.58 22.04 —2.46 20.80 22.88 —2.08 

Second ft.. 19.01 17.61 +1.40 18.62 18.97 — .35 

Third ft... 17.39 17.06 +.33 16.48 16.70 —.22 

Fourth ft.. 16.79 16.20 +.59 16.11 16.50 —.39 

' May 5 > 

Not 
Subsoiled subsoiled Difference 

PER CENT PER CENT PER CENT 

Firstfoot 21.28 21.34 —.06 

Second foot 19.02 19.11 —.09 

Third foot 19.11 18.37 +.74 

Fourth foot 16.67 17 —.33 

It will be seen that the difference between the water 
ill the soil under the two treatments becomes less each 
time the samples are taken, and that on May 5 the dif- 
ference between them had nearly disappeared. But it 
should be observed that this close agreement at the last 
time may be more apparent than real, on account of the 
fact that a rain of 1.3 inches had fallen on May 1, and 
it is possible- that time enough had not yet elapsed to 
allow an equilibrium to be established. 



J 



Effects of Suhsoiling 139 



EXPLANATION OF THE MOISTURE EFFECTS OF 
SUBSOILING 

The results stated show that subsoiling produces several very 
distinct effects, so far as soil moisture is concerned, and these 
may be stated as follows : 

1. Subsoiling increases the percentage capacity for water of 
the soil stirred. 

2. Subsoiling decreases the capillary conducting power of the 
soil stirred. 

3. Subsoiling increases the rate of percolation through the 
soil stirred, or its gravitational conducting capacity. 

In order to understand how these effects are produced by sab- 
soiling, it is necessary to have clearly in mind the nature of the 
physical changes in the soil which the operation in question sets 
up. In the small plot experiments which have been cited, the 
subsoiling had the effect of increasing the pore space in the soil 
stirred at the rate of over 245 cubic inches per cubic foot, or 14.2 
per cent. Further than this, the pore space so added consisted in 
a large measure of cavities which were so large that air and water 
would move through them in obedience to the laws which govern 
the flow of water through large pipes, rather than those control- 
ling the flow through capillary tubes. 

It must here be born in mind that the increase of space was 
made as large as it could well be, and hence that the results have 
a maximum value. 

How suhsoiling increases the water capacity of the soil stirred. — 
When a soil is broken into lumps which lie loosely together, and 
these lumps are saturated with water, the many lumps behave 
toward that water much as if each were a short column of soil 
which is in contact with standing water. The surface film of 
water which spans the pores at the surface of the saturated lump 
of soil has a definite strength, and, if the lump is not too large, 
can hold every cavity within that lump completely full of water, 
just as the lump of sugar dipped into the tea and then withdrawn 
comes forth completely filled with the fluid. But when the soil 



140 Irrigation and Drainage 

is compact, so that each portion is part of one long and continuous 
mass extending downward several feet before water is reached, 
the surface tension of the water is not strong enough to maintain 
the soil cavities full of water, and a part drains away downward. 

It is easy to demonstrate the nature of this action with a bit of 
candle wicking 2 or 3 feet long, or with two or three folds of cot- 
ton wrapping twine loosely twisted together. Placing this in a 
basin of water and letting it become saturated, if it is then raised 
out by both ends, holding it nearly horizontal and straight, the 
water very soon ceases to drip from it ; but if it is allowed to sag 
in the middle, the water will begin to drip rapidly, and will con- 
tinue to do so until a new equilibrium has been reached. The 
string will lose its water still more rapidly and completely if it is 
simply suspended from one end, when it then represents the long- 
est column of soil. 

How suhsoiling decreases the capillary conducting power of 
soils. — When large open spaces have been developed in a soil by 
any means, then every such cavity cuts off a part of the capil- 
lary passageways through which the water might travel by capillary 
conduction, thus making the amount of water which may move in 
a given direction proportionally smaller. This being true, when 
rain falls upon subsoiled ground it travels downward very slowly 
through it until after the soil has become completely filled, and 
drainage or percolation takes place. If, then, the shower is not 
heavy enough to completely fill this subsoiled layer, it is nearly 
all retained within it ; whereas, when the capillary connection is 
good, then so soon as the surface laj^er becomes wetter than that 
below, the water begins to move under the impulse of capillarity, 
and will continue to do so until a balance has been reached. 

On the other hand, when the surface of the subsoiled ground 
has become dryer through evaporation or by root action, water 
from below will not enter it as rapidly as it will soil not so treated. 
It is thus capable of acting as a deep mulch, to diminish the loss 
of water by capillary movement upward. But should conditions 
chance to be such that the whole root system of the crop has been 
developed within this subsoiled layer, then a rapidly- growing crop 
upon it might suffer for want of water when there was an abun- 



Effects of Subsoiling 141 

dance of it in the unstirred soil below, but now prevented from 
rising into the root zone by the reduced rate at which it is possible 
for the water to rise. 

This is a matter of great importance to comprehend, because 
in a humid climate, where the subsoils frequently become satu- 
rated with water, rendering them unfit for the feeding ground of 
roots, to develop a deep mulch over this by subsoiling would tend 
to maintain this lower soil permanently in a condition which 
excludes the roots of plants from it, while at the same time that 
water cannot rise into the loosened soil above, and a drought 
actually occurs when, if the field had not been subsoiled, a good 
supply of water might easily be reached by the crop. 

In the arid and sub -humid regions, the saturated subsoil is 
rarely found, except for short periods, at long intervals apart, 
and hence there is little danger from this score in subsoiling in 
these climates. 

Hoio subsoiling allows the water to enter the soil more readily. — 
From what has already been said, it will be understood that it is 
only after the subsoiled layer has become saturated that water 
begins to percolate through it, and so to store itself in the 
undisturbed layer below. But when rain enough has fallen to 
accomplish this result, then whatever else falls drops readily and 
rapidly through it, not only because there are wider channels for 
the water to move through under the stress of gravity, but because 
from an open soil the air escapes quickly and readily, thus making 
place for the water which cannot enter until the space for it has 
been vacated. The water entering the soil in time of rain or irri- 
gation is like water entering an open-mouthed jug, which cian only 
do so as rapidly as the air is permitted to escape. 

A larger percentage of the water contained hy subsoiled ground 
available to crops. — With all soils, of whatever kind, there is a cer- 
tain amount of water they contain which it is impossible for the 
roots of plants to remove with sufficient rapidity to meet their 
needs, and this amount is relatively smaller in the coarse-grained 
soils than it is in those having a finer texture. But whenever any 
soil has been subsoiled, and its water-holding power thereby 
increased, this extra amount of water beconies wholly available to 



142 Irrigation and Drainage 

the plant ; and if this amount would have been lost, either by- 
downward percolation or by evaporation from the surface, then the 
subsoiling has been a gain. 

3. Earth Mulches 

When the damp surface of a soil is covered with a 
dry layer of earth, the rate of evaporation from it is 
very much decreased. It is because of this fact that 
thorough surface tillage is able to so conserve the soil 
moisture stored in the upper four to six feet of culti- 
vated fields that fair crops may be grown with very 
little rain ; and it is in the effective handling of these 
mulches that the hope of farmers in sub -humid districts 
must be laid. 

Conditions modifying the effectiveness of mulches. — The laws 
which govern the loss of water through mulches have not yet 
been sufficiently worked out to permit a full discussion of this 
important subject, but several important facts have been defi- 
nitely settled, and may be here stated. 

In the first place, when other conditions are the same, the 
thicker or deeper the layer of loose, dry soil is, the less rapidly 
can the soil moisture pass upward through it, to be lost by 
evaporation. 

It was found, for example, that when soil covered with no 
mulch lost water in the still air of the laboratory at the rat^e of 
4.375 acre-inches per 100 days, the same soil stirred to a depth 
of .5 inches lost but 4.017 acre-inches, and when stirred to a 
depth of .75 inches lost 3.169 acre -inches in the same time. In 
another case, when the loss of water from the unmulched surface 
was 6.2 acre-inches per 100 days, stirring this same soil to a 
depth of 1 inch reduced the loss to 4 acre -inches, while stirring 
it to a depth of 2 inches left the loss but 2.8 acre -inches per 
100 days. 

So^ too, when corn was cultivated to a depth of 1 to 1.5 



Mulches to Conserve Moisture 143 

inches with a Tower cultivator, and adjacent rows were culti- 
vated to a depth of 3 inches with narrow shovels, it was found at 
the end of the season that the ground cultivated 3 inches deep 
contained 1.478 inches more water than the 1-inch cultivation 
did in the upper 4 feet, the conditions of the soil being as repre- 
sented below : 

1st foot 2iid foot 3rd foot 4th foot 

PER CENT PER CENT PER CENT PER CENT 

Cultivated 3 inches deep 23.14 23.3 21.94 22.46 

Cultivated 1 inch deep 22.7 21.08 19.65 19.58 

Difference .44 2.22 2.29 2.88 

These differences do not show the amount of water which the 
deeper mulch saved, because at several times during the season 
the rains may have brought the soil of the two kinds of treat- 
ment very close together in their water content, the results above 
being simply the final difference. They do show, however, how 
much more moist one soil was kept than the other, and, hence, 
how much better were the conditions in one case than in the 
other for plant growth. 

That the full significance of such differences in soil moisture 
in crop production may be better appreciated. Fig. 25 shows the 
growth of corn under every way similar conditions, except that 
the amounts of water in the soil in which the corn was large 
and in which it was small were as stated in the table which 
follows : 

Moisture in soil Moisture in soil 
of largest corn of smallest corn 

PER CENT PER CENT Difference 

First foot 13.29 10.18 3.11 

Second foot 17.23 16.33 .9 

Third foot 19.17 18.63 1.08 

Fourth foot 16.21 15.48 .73 

These differences, it will be noted, are much smaller than in 
the ease cited above. But let it be observed that the difference in 
the surface foot here is very much larger than there, and it is the 
shortage of water in this layer which is chiefly responsible for the 
difference in growth shown in the figure. 



144 



Irrigation and Drainage 



The character of the mulch, also, has an important influence 
on the amount of water which is permitted to escape through it. 
Thus, it was found that when the same soil was covered to a depth 




Fig. 25. Difference in growth of corn where there is a difference of 
3 per cent of soil moisture in the surface foot. 

of 2 inches with mulches of different kinds, the observed loss of 
water per 100 days was as stated below : 

INCHES 

Through 2-inch mulch of coarse sand ; l.l 

" " " " black marsh soils 3.0 

" " " ' fine clay loam 3.9 

" " " " dry peat 2 

" " " " clay loam, crumb-form 2.8 



From these results it is seen that a coarse-grained texture 
produces a better mulch than one extremely fine ; that is, the loss 
of water by evaporation through the coarsest sand was less rapid 
than it was through the fine sand, and it was more rapid through 
the finely powdered clay loam than it was through the same soil 
left in the crumbled condition in which we usually fiud it when 
the soil is in good tilth. The small loss from the peat mulch, too, 
was due largely to the fact that it did not rub down to a fine 
texture. 

Just why this law holds for soil mulches cannot now be stated, 
except that it seems evident that the water is not lost by direct 
evaporation at the surface of the damp soil, for in that case we 
should expect the largest losses to take place from the mulches 
having the most open structure, and the least when the diameter 



Mulches to Conserve Moisture 145 

of the pore spaces is smallest, but which observation proves not 
to be true. The only explanation which now occurs to the writer 
for the law is, that even in the air-dry condition of soil, the film 
of moisture still investing the soil grains, although so extremely 
thin, is subject to the same disturbance by evaporation at the 
exposed surface that it is when that film is much thicker, as in the 
case of soils containing the right amount of moisture for plant 
growth, and when evaporation from the surface takes place 
rapidly. 

Earth mulches lose in effectiveness with age. — When a good 
earth mulch has been developed, it does not remain equally effec- 
tive for an indefinite period, even if no rain falls upon it. This is 
particularly true early in the season, when the amount of soil 
moisture is high, and when it tends to creep into the lower part 
of the mulch, saturating it and causing the open texture to 
disappear by breaking down the crumb structure, and thus restor- 
ing the original and normal capillary power. A soil mulch devel- 
oped to a depth of two or three inches thus grows gradually 
thinner with age by reverting to the original condition. This be- 
ing true, it is necessary, when the greatest protection is desired, 
to repeat the stirring of the soil as often as observation shows that 
its effectiveness has been impaired. 

Mulches that are not made from soil. — By far the largest part 
of the protection offered against the loss of water by surface 
evaporation from the soil is and must be furnished by mulches 
developed from the soil itself. But it should be understood that 
all vegetation growing upon the surface of a field, whether it 
completely covers the ground or not, exerts a protective influence, 
tending to diminish the loss of water from the surface of the 
ground. This protection comes partly from shading the ground, 
partly from a reduction of the wind velocity close to the surface, 
and partly from the tendency of vegetation, by the transpiration 
from its foliage, to saturate the air with moisture, and so reduce 
the rate of evaporation which otherwise would be possible. 

Even in pastures where the grass is short, if it is only close 
and completely covers the ground with its foliage, the mulching 
influence is marked. Hence, in order to get the largest returns 



146 Irrigation and Drainage 

from the natural rainfall on pasture land, great care should be 
taken to keep it in such condition that the whole surface is well 
and closely covered with vegetation. Of course, the same remarks 
apply to meadow lands. 

Too close pasturing is very wasteful in every way. The 
animals themselves are not fed properly, the grass is not permitted 
to have foliage enough for the most vigorous growth, and so much 
of the surface of the ground is exposed to the sun that evapora- 
tion directly from the soil is rapid and a dead loss, not only doing 
no good in itself, but throwing out of use the upper layer of soil, 
in which the nitrifying processes should be permitted to go for- 
ward rapidly, because it is too dry for them. 

The surface dressing of meadows with a good coating of 
farmyard manure, and then harrowing this thoroughly to spread it 
evenly over the surface, is extremely beneficial, not simply because 
of the plant-food which it contains, but because of the mulching 
effect which it furnishes to shade the naked spots of soil and 
those which are only thinly covered. When this dressing is 
applied very early, and is early spread over the surface, while 
the soil is yet damp, it, of course, does the most good, both as a 
mulch and as a plant-food ; for then fermentation goes on better 
in the manure, and the moisture dissolves out the soluble parts 
and conveys it to the roots of the grass. Then, too, in the case 
of thin meadows, if new grass and clover seed are added at the 
same time, before the harrowing, much of it will be sufficiently 
covered by the harrowing and shaded by the manure to allow it to 
germinate, and thus thicken up the meadow and bring it back to 
its proper condition. 

Harrowing and rolling small grain after it is up. — When the 
ground is closely covered with plants, as in the case of oats, 
wheat and barley sowed broadcast or in close drills, advantage 
has sometimes been found in either harrowing the ground or in 
rolling it for the express purpose of changing the character of the 
surface. The changes thus wrought have sometimes a double 
effectiveness, in that a thin mulch is produced which in a meas- 
ure reduces the direct loss of water through the surface soil by 
evaporation from it ; and in breaking up a crust which forms 



Early Tillage to Conserve Moisture 147 

over plowed fields when a considerable evaporation has taken 
place from the wet surface, and which, on account of the shrink- 
age and of the salts brought to the surface by the soil water, tend 
to close up the soil pores, and thus interfere with the proper 
entrance of air to it, which is essential to the best results. Roll- 
ing in such cases will seldom do much good, except where the 
ground was left somewhat uneven at the time of seeding, either 
by the drill ridges or by those left by the harrow, or unless there 
are many small lumps, which the rolling tends to break down, 
forming from them and the ridges, or both, a thin mulch. The 
harrowing in such eases has a wider range than rolling, and is 
often likely to be more effective. But neither of these treat- 
ments should be given except when the soil of the field is dry 
and crumbly at the surface, for otherwise no mulch will be formed, 
and the effect would be to increase rather than diminish the loss 
of water from the soil by surface evaporation from it. 

4. Early Tillage to Conserve Moisture 

It has already been pointed out that tillage to 
conserve moisture is most useful in humid climates 
when it is applied as early in the season as the condi- 
tion of the soil will admit. But the case is stated in 
the most general terms when it is said that tillage, 
to save moisture, should be given to the soil just as 
soon after the wetting of the surface as it is possi- 
ble to do so without puddling or otherwise injuring 
its texture. 

Let it be fully understood that tillage to save soil 
moisture is concerned almost wholly with the saving 
of that which has penetrated the soil to a depth exceed- 
ing that of the mulch developed by stirring, As a 
thoroughly effective soil mulch cannot be readily made 
having a depth less than 2 to 3 inches, it follows that 



148 Irrigation and Drainage 

tillage to conserve soil moisture is chiefly concerned 
with saving moisture which has penetrated the ground 
to a depth exceeding 2.5 to 3 or more inches. The 
moisture which is caught and held by the soil closer 
to the surface than stated must usually be taken up 
directly by the surface feeding roots, or it must be 
lost by surface evaporation. 

When the snows and frosts of winter have melted, 
and the earliest spring rains have come, the soil is 
usually left so moist as to be fully saturated with 
water to a depth exceeding 1, 2, and even 3 feet, 
according as the snows or rains have been copious or 
light. At the same time, the texture of the surface 
soil has been so changed as to place it in the very 
best possible condition for rapidly conveying the deeper 
soil -water to the surface, where, if the sun shines and 
a brisk, drj^ wind is blowing, it will be lost with great 
rapidity, sometimes in single exceptionally favorable 
days amounting to 2, 3, and even 4 pounds per square 
foot per day, equivalent to more than 40, 60 and 80 
tons per acre. 

But these high rates of loss are not maintained, 
fortunately, for long periods of time, even when there 
has been no effort made to prevent them. We have, 
however, measured losses during seven days amounting 
to 9.13 pounds per square foot, or at a daily rate of 
1.3 pounds; and in four days a rate as high as 1.77 
pounds per square foot. Under extremely favorable 
conditions, and where the surface of the soil was kept 
continuously wet, we have measured a mean daily loss 
by evaporation as great as 2.37 pounds for fine sand, 



Early Tillage to Conserve Moisture 149 

and 2.05 pounds for a clay loam, per day and per 
square foot. 

As soon as the surface of the soil becomes air -dry, 
the rate of evaporation from it is very much slower, 
for in this condition it does not conduct the water 
upward as rapidly as when nearly saturated. Early 
tillage contributes to this end, and thus greatly di- 
minishes the losses which would occur early in the 
season. 

There is no tool made which produces a more 
effective mulch than the common plow, which cuts off 
completely a layer of soil of the depth desired and 
lays it down bottom up in a loose, crumbled condition, 
reducing the capillary conducting power to the mini- 
mum. It is not possible, however, to use the plow as 
early in the season as some of the other tools, like the 
harrow ; neither is it possible to cover the ground as 
rapidly with it. Further than this, it is often unde- 
sirable to stir the soil as deep as it must be worked 
with the plow, in order to make a good mulch ; and 
so one or another form of harrow is used instead. 

When small grains are sowed on fall plowing, or 
on corn or potato ground without plowing, it is 
important to start the surface -working tools at the 
very earliest possible moment, not simply to save 
moisture by developing a mulch, but to aerate and 
warm up the surface soil, so that the nitrates may 
"begin to be developed and placed in readiness for the 
crop which is to follow. It is this saving of moisture, 
and the early and abundant development of soluble 
plant -food, which is invariably associated with and the 



150 Irrigation and Drainage 

direct result of a thorough preparation of the seed- 
bed, which has always led the most successful farmers 
to insist upon the importance of a good seed-bed. 

Let it be remembered that it is the early stirring 
of the soil, rather than the early planting of the seed, 
which is the all -important point to be insisted upon. 
Nothing is gained by putting seed in a soil which is 
too cold ; but several days may often be saved in bring- 
ing the soil to the right temperature by stirring a suf- 
ficient depth of it for the seed-bed, and getting rid 
of the surplus water which it contains by cutting it 
loose from the wet soil below, and at the same time 
concentrating the heat from the sun in this stirred 
layer, because loosening it has made it a poor con- 
ductor to the unstirred cold soil below it. 

Even when ground is not to be planted until quite 
]ate, as in the case of corn and potatoes, it is a far 
better practice to plow as early as other labor will per- 
mit, than to leave it unstirred until near the planting 
time, because the early fitting develops plant -food and 
gets it in readiness for the crop ; because it saves 
moisture ; because it prevents clods from forming, and 
insures a more perfect tilth, and because it allows one 
and sometimes two crops of weeds to be killed before 
the planting. This last advantage is a very important 
one, because weeds can be killed much more cheaply 
and effectively when there is nothing on the ground 
in the way, and because it is a very wasteful practice 
to permit weeds to start in a field, to use up both the 
moisture and the plant -food which will be needed by 
the crop. It is much better to plant late, and take 



Ploiving Under Green Manures 151 

time enougli to have everything in the best possible 
condition, than to rush the seed in early and expect 
to do the fitting and weed -killing afterward. 

The importance of observing the practice here 
pointed out increases more and more as we pass from 
the more hnmid climates to the semi -humid ones. 
Be it remembered that it is important not simply from 
the soil -moisture side, but from the plant -food side as 
well; for plant -food cannot be developed in the soil 
without the right conditions of moisture, temperature 
and air, all of which are secured by early, thorough and 
frequent tillage before the seed is in the ground. 

5. The Danger of Ploiving Under Green Manures 

In both humid and sub-humid climates, where irri- 
gation is not practiced, the use of green crops for ma- 
nures in the spring cannot be looked upon as always 
a rational practice, unless it be on grounds which are 
naturally sub -irrigated, or for other reasons are natu- 
rally too wet. The difficulties standing in the way of 
this practice are these : If the green manure crop 
should be rye, or anything of that character, its ten- 
dency to remove from the soil all of the nitrates and 
other soluble plant -foods as rapidly as they can be 
formed leaves the soil for the time being impover- 
ished ; and it can be readily understood that if another 
crop like corn or potatoes is put at once upon the 
ground, in weather when germination takes place 
quickly, this crop would find itself placed under con- 
ditions in which it will be forced to wait, or at best to 



152 Irrigation and Drainage 

grow slowly, until time enough shall have elapsed for 
the processes of fermentation to be set up in the green 
crop which shall reconvert it into available plant- 
food. But if the spring should chance to be a dry 
one, so that the crop of green manure has itself left 
the soil deficient in moisture, or if the capacity of the 
soil for moisture is naturally small, then there will be 
present in the soil neither moisture enough to make 
the green crop turned under ferment rapidly, nor to 
enable the planted crop to make the best growth, even 
where there is an abundance of plant -food in the 
soil. 

The sowing of a catch crop in the fall in humid 
climates is not open to the same objection, for then 
this crop has a tendency to gather up available ni- 
trates which develop during the warm part of the fall, 
after the crop has been taken off the ground, and to 
carry them through the winter in an insoluble form, 
so that they are not lost by drainage. But to bring 
them into requisition, especially if the season or soil 
is at all dry, it is important that this should be turned 
under early, and a sufficient interval of time allowed 
to intervene for fermentation to take place before the 
seed of the new crop is put upon the ground. 

In sub -humid climates, on soils that are not sub- 
ject to washing, it is very doubtful if there is any 
advantage to be gained from catch crops, as such, 
even when sown in the fall ; for in those cases there is 
neither winter nor spring leaching of the soil, and as 
there is naturally a deficiency of soil moisture, the indi- 
cations are that very early fall plowing, to develop a 



Summer Fallowing and Soil Moisture 153 

new mulch to lessen further evaporation during the 
fall and winter, and to permit nitrification in the fall to 
be carried forward, is likely to leave the soil in a much 
better condition for the next season, both as to moisture 
and available nitrates, than could be hoped for by the 
other method. 

It is not only difficult to get a good catch crop in the 
fall on account of deficient moisture, but there is during 
the growing season of the sub -humid climate so little 
moisture that a rapid rate of nitrification in the soil 
is impossible, and hence all the time which can be had 
for this purpose is needed in order to have enough 
nitrates developed for the crop the next year. 

6. Summer Fallowing in Relation to Soil Moisture 

The old practice of summer fallowing, which it has 
been the fashion for writers on agricultural chemistry 
to discourage of late years, has really much more of 
merit in it, as indeed practical experience has proved, 
than has been recently taught. It is not here intended 
to convey the idea that there are not soils and climates 
in which, in the majority of seasons, it would be better 
not to summer fallow, on account of there being danger 
of an excessive development of nitrates, which would be 
lost by drainage ; but there is much to suggest that in 
rich soils which are usually deficient in soil moisture, 
as in many sub -humid sections, there is not mois- 
ture enough in a single year to develop the requisite 
amount of plant -food and to mature the crop as well, 
and hence, that some form of summer fallowing, or 



154 Irrigation and Drainage 

practice which is equivalent to it in effect, will be found 
to give better results than steady cropping, either with 
or without catch crops. 



INFLUENCE OF SUMMER FALLOWING ON SOIL MOIS- 
TURE AND ON PLANT -FOOD 

In a study on the influence of summer fallowing on the water 
content of the soil, it was found that the effect still showed, even 
at the end of the following season, after a crop had been matured 
on the ground. In order to show how great this influence may 
be, the results of the study are cited here, giving first the con- 
dition of the soil in the spring, when the fallowing experiment 
was begun. The results cited are from three adjacent plots, the 
middle plot being the one bearing the crop. The table which 
follows shows the water content of the plots as given by three 
determinations, on May 22, June 11, and June 17, the averages 
being given in every case, and the data from the two fallow 
plots being combined: 



0-12 inches 

12-18 " 

24-30 " 

36-42 " 

48-52 " 

Mean 19.20 18.92 



Here it will be seen that there is a slight tendency for the 
ground left fallow to be a little wetter than that which was to 
bear the crop, but this difference is not as large as the table 
shows, because the fallowing effect had begun to show its in- 
fluence somewhat when the last two sets of samples were taken, 
corn having already begun to grow upon the intervening plot. 

At the end of the growing season, August 24, the difference 



Gro^^nd to be 
left fallow 


Ground not to be 
left fallow 


PER CENT 


PER CENT 


23.63 


21.49 


19.78 


18.57 


18.06 


18.13 


15.50 


17.48 


19.03 


18.91 



Summer FaUotving and Soil Moisture 



155 



in the water content of the soil under the two treatments was 
found to be as given in the table below : 



Not fallow ground near by 
Fallow ground Not fallow ground Timothy and Clover 





No crop 


Corn 


bluegrass 


in pasture 




PER CENT 


PER CENT 


PER CENT 


PER CENT 


0-6 inches 


16.23 


6.97 


6.55 


8.39 


6-12 " 


17.74 


7.8 


7.62 


8.48 


12-18 " 


19.88 


11.6 


11.49 


12.42 


18-24 " 


19.84 


11.98 


13.58 


13.27 


24-30 " 


18.56 


10.84 


13.26 


13.52 


40-43 " 


15.9 


4.17 


18.51 


9.53 



In the first half of this table, where the soils are closely 
similar and entirely comparable in every way, it will be seen 
that the ground bearing no crop is much more moist than is 
that on which the corn was grown ; and since a good degree of 
moisture in the surface foot of soil is absolutely indispensable 
to the processes which develop the available nitrates, it can readily 
be seen how much more favorable were the conditions for the for- 
mation of nitrates on the fallow ground than they were on the 
ground which was not fallow. In the last two columns of the 
table, there has been set down, for the sake of comparison, the 
results of moisture determinations at corresponding depths on 
lands bearing pastured clover in one case and hay in the other. 
These samples were taken from essentially the same kinds of soil, 
and but a short distance from where the other samples were 
taken, and illustrate in a very forcible manner how thoroughly 
the surface foot of soil in a dry time loses its moisture when it 
is occupied by a crop, and how unfavorable are the conditions 
for nitrification in the soil when compared with those offered by 
the fallow ground. 

In the following spring, after the frost was out of the ground, 
and the fall and winter rains and snows had given their moisture 
to the plots under experiment, samples of soil were again taken, 
to learn what the relative conditions were at this time, and the 
results found are given in the table below, where both the per- 



156 



Irrigation and Drainage 



centage of water in the soil and the number of pounds of water 
per cubic foot are given : 

Table showing the water content in the spring, in soil tvhich the year before had 
been fallow and not falloio 



Depth Fallow 
of sample per cent 

First foot 19.43 

Second foot..,. 20.55 

Third foot 18.56 

Fourth foot.... 17.78 

Sum 



Not 
fallow 


Difference 


Fallow 


Not 
fallow 


Difference 


PER CENT 


PER CENT 


LBS. 


LBS. 


LBS. 


16.61 


2.82 


15.01 


12.83 


2.18 


17.76 


2.79 


16.4 


14.17 


2.23 


16.09 


2.47 


17.47 


15.15 


2.32 


15.11 


2.67 


17.44 


14.82 


2.62 



66.32 



56.97 



9.35 



This table shows that the fallow ground starts out in the 
spring with 9.35 pounds of water to the square foot more than 
the ground not fallow did in its upper four feet, besides having 
a much higher percentage of available nitrogen in the soil. How 
much greater the available nitrogen was is not known, except 
that in another trial, ground which had- been fallow the year 
before produced practically the same yield as did a strip which 
received a good dressing of farmyard manure. 

At the end of harvest the same year, samples of soil were 
again taken on the ground which had been fallow and on that 
which had not been fallow, the results standing as shown below: 



Table showing the water content of soil at the end of harvest, which the 
preceding year had been fallow, and had not been fallow 



Depth 
of sample 

First foot . . . 
Second foot . 
Third foot... 
Fourth foot. . 

Sum 34.13 



Fallow 


UUUU WILU 

Not 
fallow 


oais ^ 

Difference 


' XJTTV 

Fallow 


unu Willi 

Not 
fallow 


uaimy — > 
Difference 


LBS. 


LBS. 


LBS. 


LBS. 


LBS. 


LBS. 


6.01 


3.74 


2.27 


9.06 


7.08 


1.98 


9.65 


4.45 


5.20 


11.90 


10.10 


1.80 


9.54 


9.30 


.24 


12.48 


10.60 


1.88 


8.93 


8.43 


.50 


14.07 


11.52 


2.55 



25.92 



8.21 



47.51 



39.30 



8.21 



The data of this table show very clearly that summer fallow- 
ing exerts a marked influence upon the relation of the soil to 



Old System of Iiifertillage 157 

water, and one which is great enough to modify the water con- 
tent of the soil throughout the whole of the following season under 
crop. The table shows that where oats were grown, the soil, 
when the crop had been harvested, contained 8.21 pounds of 
water per square foot, or 1.57 inches more than did the ground 
which had not been summer fallowed the year before. The same 
difference also existed on the barley ground, and in both cases 
notwithstanding the fact that larger yields of both straw and 
grain had been produced on the fallow ground. 



7. The Old System of Intertillage 

The old system of horse -hoeiug, introduced by 
Jethro Tull in England, and modified by Hunter, and 
still later by Smith, at Lois-Weedon, has much to rec- 
ommend it on fertile soils, in which there is a deficiency 
of soil moisture, as is the case in the sub -humid 
regions of this country. Tull was a close observer, 
and early learned to appreciate the great advantage 
of thorough tillage, not only in conserving soil mois- 
ture, but also in developing available plant -food. He 
strongly advocated planting in drills, so as to admit 
of thorough and frequent stirring of the soil and with 
the aid of the horse. 

Hunter modified Tull's system by laying out his 
fields in strips about 9 feet wide, every other one of 
which was sown, while the intermediate ones were 
left naked, and were frequently cultivated through the 
season, and kept free from weeds. In the fall of the 
year the bare strips were sown, and the others, which 
had borne the crop, were plowed up and tilled in a 
similar manner. His method amounted to a system 



158 Irrigation and Drainage 

of summer .fallowing, as that practice is now generally 
understood, except that it possessed one important ad- 
vantage : namely, his strips being so narrow, and hence 
so numerous, that both the moisture saved by the til- 
lage and the nitrates developed became available to 
the plants growing along the margin. Further than 
this, a part of the rain which fell upon the strips, 
both by its lateral capillary movement and by the 
development of roots into this unoccupied ground, 
contributed to the growth of the crop as though it 
had been partially irrigated, or its rainfall had been 
increased,- which in fact it had. 

The Rev. Mr. Smith, at Lois-Weedon, in North- 
amptonshire, raised wheat very successfully by still a 
different modification of TulPs idea. His practice 
was to sow about one peck of seed to the acre, by 
dropping the grains 3 inches apart in three rows 1 foot 
apart, and leaving a space 3 feet wide unplanted be- 
tween each group of three rows. These strips were 
thoroughly tilled until the wheat was in bloom, and 
kept free from weeds. He even went to the extent of 
trenching the naked strip, bringing up some of the 
subsoil and putting the surface loam into the trenches. 
By his thorough tillage, thorough aeration and con- 
servation of soil moisture, he was able to maintain a 
yield of 18 to 20 bushels per acre without manure. 

These cases of old and now generally abandoned 
practice are called up here because they involve a 
principle which, when correctly applied, is of great 
importance in sub -humid climates, where water for 
irrigation is not available. The principle referred to 



Old System of Intertillage 159 

is that of using the rain which falls upon an acre of 
ground to produce a crop on one -half of that same 
area. For this, as a matter of fact, was the essential 
thing which the Lois-Weedon system did. It is evi- 
dent enough that in a country where the rain which 
falls is only one -half the amount which is needed to 
produce remunerative crops, if that water can be 
brought to use on one -half of the area, then a fair 
crop on one -half of the ground may reasonably be 
expected. 

The important matter, then, is to devise a system 
of planting for the various crops which shall permit 
the rain which falls upon the unused area to be 
brought within reach of the plants growing upon the 
occupied ground. For all crops which are grown in 
hills or in rows, like inaize, potatoes, and various 
vegetables, the problem is simple enough, as it resolves 
itself into the single question of how many plants can 
be matured uj^on the ground with the available water, 
allowing for unavoidable losses. This fixes the dis- 
tance between the rows and the distance between the 
hills in the row. In countries where there is an 
abundance of water, or where irrigation is practiced, 
plants may be brought so close together that the limit- 
ing factor is amount of sunshine, or available plant- 
food in the soil, or air about the plant ; but in sub- 
humid regions, the limiting factor is water alone, and 
the distance between plants must be made such, if 
necessary, that the roots of one will not encroach upon 
the feeding ground of another. 

The roots of the maize plant commonly spread 



160 Irrigation and Drainage 

laterally to a distance of 3.5 to 4.5 feet ; hence, if 
necessary, the rows of corn might be placed as far as 
7 to 8 feet apart, and yet be able to take moisture 
from the whole field. Taking the extreme case of 
rows 8 feet apart and plants 2 feet apart in the row, 
the number of plants per acre would be 2,725. Sup- 
posing each plant to produce a large stalk and large 
ear, the total weight of diy matter for the acre might 
be 2,157.5 pounds, giving 18.32 bushels of shelled 
corn. This yield of dry matter per acre would call 
for only 2.577 acre -inches of water to produce it, at 
the rate of the results which have been obtained from 
52 trials in Wisconsin. 

Potato roots spread laterally to the distance of 2 
to 2.5 feet ; hence these might be planted in rows 4 
to 5 feet apart without having the roots overlap in 
the feeding ground. The chief advantage of wider 
rows for potatoes in the sub -humid climate comes in 
its permitting intertillage after the vines have reached 
full size, and thus better conserving the scanty mois- 
ture, so important in the later development of the 
tubers, and which would travel laterally by capillarity 
toward the roots in case they did not reach the center. 
The table which follows shows the actual distribution 
of soil moisture in the upper 18 inches of a potato 
field in which the rows extended east and west, and 
were planted 3 feet apart, under flat cultivation : 



I 



Old System of IniertiUage 161 



Table showing the distribution of moisture in a potato patch, June 27 





Midway 
between rows 


Nine inches 
south of row 


In the row 


Nine inches 
north of row 


Depth of sample 


PER CENT 


PER CENT 


PER CENT 


PER CENT 


0-6 inches 


23.50 


18.37 


17.80 


23 


6-12 '' 


19.03 


18.13 


17.40 


18.50 


12-18 " 


20.73 


21.43 


19.53 


21.40 



0-18 '' 20.99 19.31 18.24 20.97 

At the time these determinations were made, the 
potato vines were about one -half full size. It will be 
seen that the moisture had been withdrawn from the 
soil more completely at 18 inches directly below the 
center of the hill than it had at 18 inches on either 
side. It does not follow from this, however, that the 
plants were not receiving important additions of soil 
moisture from the soil in the center of the row. In 
our work in irrigating potatoes, where the rows were 
30 inches apart, and where ridge culture was adopted, 
the water being applied in furrows about 9 inches 
wide, it was found that on the boundary between the 
irrigated and non- irrigated areas, the second row of 
potatoes from the last water furrow had its yield 
increased on the average, in 1897, 7.9 bushels per 
acre, or 3.2 per cent of the yield of merchantable 
tubers, grown on the land not irrigated. That is to 
say, the lateral capillary movement of the water in 
irrigation influenced the yield to that extent through 
a distance of about 40 inches. 

In the case of corn, the second rows beyond the 
last irrigating furrow showed the influence of the 
water to the extent of 2.2 per cent of the non- 

K 



162 Irrigation and Drainage 

irrigated yield, and through a distance of about 58 
inciies. 

Then, again, in the case of some experimental plots 
of oats which were separated by a naked strip 2 feet 
wide, and kept free from weeds by surface hoeing, the 
following distribution of water was found on July 
19, 1889: 

Table shoivtng distribution of soil moisture ia oats and in adjacent 
fallow strip 2 feet wide 





In oats 2 ft. 
from path 


In oats 1 ft. 
from path 


At edge 
of oats 


In center 
of path 


Difference 


Depth of sample 


PER CENT 


PER CENT 


PER CENT 


PER CENT 


PER CENT 


0-6 inches 




8.08 




11.43 


3.35 


6-12 " 




7.51 




11.80 


4.29 


12-18 " 




10.61 




15.42 


4.81 


18-24 '' 




14.01 




18.78 


4.77 



0-24 *' 10.40 10.05 10.70 14.35 

It will be seen from these percentages that there is 
a very marked higher per cent of water in the fallow 
strip than there is immediately adjacent to it in the 
oats, and from this it might be inferred that the oats 
was not being fed from the fallow strip. This inference, 
however, would not be correct, for it was found that 
the yield of oats on a strip 1 foot wide, on the south 
side of the path, was 39 per cent larger than from a 
corresponding area in the center of the plot 12 feet 
wide, while the yield on the north side of the path 
was 28.7 per cent larger, showing very clearly that 
there was better feeding in consequence of the narrow 
2 -foot path. 

In view of such facts as these, and practical experi- 



Old System of IntertiUage 163 

ence, it is not unreasonable to expect that where there 
is a deficiency of water in the soil, the small grains 
may be sown in narrow strips of 4 to 6 drill rows, 
9 inches apart, separated by naked strips 30 inches 
wide, which may be cultivated to yield up their mois- 
ture and developed nitrates to the growing grain on 
either side, and thus mature heavier crops of well- 
fiUed grain than would be possible if the seeds were 
scattered evenl}^ over ihe whole surface, none of which 
could be cultivated. 

Such a practice as is here suggested is manifest!}' 
summer fallowing, but in a very different way, and 
for quite a distinct purpose, from that usually had in 
mind. Of course, it would not be urged, except on 
soil and in climates in which there is an insufficient sup- 
ply of soil moisture to mature the crop under ordinary 
methods of handling. The method, however, has a 
rational basis for sub -humid climates and for the 
lighter soils of small water capacity in the more humid 
climates; but it cannot be hoped that it will, under 
these conditions, give as large yields per acre when 
figured upon the whole area as the closer planting on 
the soils better supplied with soil moisture. Neither 
can it be expected that crops can be raised as cheaply 
by this method as by the ordinary methods. All that 
can be asserted, or can be reasonablj^ expected, is that 
better crops can be raised by it- in sub -humid climates 
and on the lighter soils in humid climates, than can 
be raised by the ordinary methods. It is not an easy 
matter to adapt the method either to growing hay or 
to maintaining pastures of the ordinary sort. 



164 Irrigation and Drainage 



8. Frequency of Tillage to Conserve Soil Moisture 

Tillage to conserve soil moisture, like water for irrigatiorij 
cannot be applied except at an increased cost of production. 
Hence, to cultivate a field when there is nothing to be gained 
from it is to be avoided. In the early part of the growing sea- 
son, when the soil is so fully charged with moisture that a small 
rain easily causes the soil granules to coalesce and destroy the 
effectiveness of mulches, it is often desirable to repeat the culti- 
vation or harrowing as often as there has been a shower of suffi- 
cient intensity to establish good capillary connection between 
the stirred and unstirred soil. 

It is often of the greatest importance that this reestablish- 
ment of the mulch should take place at the earliest possible 
moment, not only because of the rapid loss of water from wet 
surfaces, but because of the fact that, when the surface soil has 
reached a certain degree of dryness while the deeper soil is yet 
wet, the moisture of the surface layer so strengthens the upward 
movement of soil moisture into that layer that not only is all 
of the rain held at the surface, but a very considerable amount 
of the deeper soil w^ater is brought there also. Our studies have 
proved, both by observation and by repeated experiment, that 
wetting the surface of the ground may leave the deeper soil 
actually dryer than it was before, and if the new mulch is not 
early developed the rain may leave the surface four feet dryer 
than it would have been had the rain not occurred. 

Then, too, in the early part of the year, there are so many 
advantages to be gained through frequent stirring of the soil, - 
other than the saving of moisture, that the slightest reason for 
going over the ground again should lead to its being done. But 
as the season advances, and the soil has become dryer to con- j 
siderable depths, then the desirability of frequent stirrings of ' 
the surface to develop or restore the texture of the mulch, is 
much less. This is so, partly because when the surface of the 
ground is dry, it is an excellent mulch, even though it is quite 
firm and close in texture ; but also, because the smaller showers 



Ridged or Flat Cidiivation 165 

of the later season are largely retained very close to the surface, 
so that stirring the surface may hasten the evaporation of it, and 
at the same time prevent a part of it from being conducted 
downward into the soil by capillarity. 

Further than this, in the latter part of the season many plants 
in humid climates put out new roots, which reach up extremely 
close to the surface, in order to take advantage of the showers 
w^hose waters are retained there ; and tillage at once after a 
rain may do positive injury to the crop, by destroying these roots 
before they have conveyed the soil moisture to the plant, heavily 
laden with plant-food, as it is likely to be under these conditions. 

9. Proper Dei)th of Surface Tillage and Eidged or 
Flat Cultivation 

It will be readily inferred, from what has already been 
said, that the best depth of tillage will vary with the season. 
Early in the season it should almost invariably be deep, not less 
than 2 to 3 inches, but rarely should it be deeper than this. The 
deep stirring in the spring is to develop fertility by thoroughly 
aerating the soil and making it warm, so that the nitrates are 
rapidly formed. Later in the season the cultivation should be- 
come more and more shallow, until, as already pointed out, it 
should be finally abandoned altogether. 

When it is stated that the early tillage should have a depth of 
2 to 3 inches, this should be understood as meaning that the 
whole surface of ground not occupied by the plants should be 
stirred to this depth, and some tool which actually displaces the 
whole of the soil to a uniform depth does the best work. As a 
rule, the field should not be furrowed with deep grooves and 
ridges, for this method early dries out too large a volume of the 
soil, and thus lessens its productive power. Indeed, it should 
always be kept in mind that the surface soil in humid climates is 
the most valuable soil of the field; and for this reason, after the 
period of stirring for fertility is passed, as little should be moved 
and allowed to become dry as will answer the needs of the mulch, 
because in this condition the soil is valueless in plant feeding. 



166 Irrigation and Drainage 

Throwing a f eld iuto ridges with deep furrows between, as is 
done with some of the wide -shovel cultivators, and as used to 
be done generally in laying corn by, has little to recommend it 
except on flat fields of stiff, heavy soil, in wet climates or seasons. 
The chief objection to the ridges and furrows is that they greatly 
increase the evaporating surface and the amount of soil which is 
thrown out of use. In the case of potatoes, however, especially 
on the heavy soils, the last cultivation should be to hill them in 
order to form a loose, deep, mellow soil, in which the tubers may 
form and expand without meeting with excessive resistance. 
Indeed, it is quite doubtful whether there are many soils in which 
potatoes will not do better if hilled to some extent the last thing 
before the vines spread to cover the ground. The earlier 
cultivation should by all means be flat. 



10. Rolling in Relation to Soil Moisture 

The roller has an extensive nse in many localities 
in fitting land for crops in the spring or fall. It 
shonld be nnderstood, however, that when the surface 
of a field is finished with a heavy roller, it is left in 
a condition in which its moisture will be rapidly lost, 
and for several reasons : 

1. Firming the surface reestablishes the capillary 
connection with the soil below, and the moisture is 
brought to the surface quickly from depths as great 
as four feet. The appearance to the eye is that the 
ground is made more moist, and so it is at the sur- 
face, as a matter of fact, but it must never be for- 
gotten that this is at the expense of moisture stored 
deep in the ground. 

2. Rolling leaves the surface smooth and even, 
so that it absorbs heat rapidlj^ from the sun on a 



I 



Rolling in Relation to Soil Moisture 167 

clear day, and becomes warmer below the surface than 
ground not rolled. This hastens the rate of evapo- 
ration from the surface. Then, too, this smooth sur- 
face allows the wind velocity to be much greater close 
to the ground, and on this account the loss of water 
is increased. 

It is often desirable to use the heavy roller in fit- 
ting ground for seed, and sometimes for the express 
purpose of bringing an increased amount of moisture 
to the seed, in order to hasten or to ensure germi- 
nation when the soil has become dry. But when this 
has been found desirable, the roller should immedi- 
ately be followed with a light harroAV, in order to 
restore a thin mulch, which shall check the loss by 
evaporation from the surface without at the same 
time preventing the rise of water from below to mois- 
ten the soil about the seed. 

The press -drill, which has been invented to assist 
germination, and avoid some of the bad effects of the 
roller, is a tool employing a sound principle. The 
seed is well covered to begin with, and then the soil 
directly above it is firmed by the press -wheel, while 
the intervening soil is left loose, to act as a mulch 
and diminish the loss of water, which would be inevi- 
table with the roller. This tool, however, has a much 
safer application in the sub -humid regions than it 
has in the East, where the soil in the spring is natu- 
rally more moist, and where, for this reason, there is 
danger of the seed being so closely covered that an 
insufficient amount of air gets to it to enable it to 
germinate properly. 



168 Irrigation and Drainage 

11. Lessening Destructive Effects of Winds 

111 sub- humid climates, especially like those of our 
western prairies, where there is a high mean wind 
velocity, and in the level districts of humid climates, 
where the soils are light and sandy, with a small 
water capacity, and which are lacking in adhesive 
quality, the fields may suffer greatly at times, not 
onl}" from excessive loss of moisture, but the soil itself 
maj^ be greatly damaged by drifting caused by the 
winds. Under such conditions, it is a matter of great 
importance that the wind velocities close to the sur- 
face should be reduced as much as possible. 

We have, in Wisconsin, extensive areas of light 
lands which almost every j'ear suffer severely from 
the drifting action of the winds. On these lands, 
wherever broad open fields lie unsheltered by any 
windbreak, the clearing west and northwest winds 
which follow storms not only rapidly dry out the soil, 
but often sweep entirely awaj- crops of grain after 
they are 4 inches high, uncovering the roots by the 
removal of 1 to 3 inches of the surface soil. It has 
been observed, however, in these districts, that where- 
ever there are windbreaks of any sort, even such slight 
barriers as fences and even fields of grass, a marked 
protection against drifting has been experienced for 
several hundred feet to the leeward of them. 

In the case of groves, hedgerows, and fields of 
grass, the protection results partlj- from their ten- 
dency to render the air which passes across them more 
moist, and partl}^ by lessening the surface velocity of 



Lessening Destructive Effects of Winds 169 

the wind. The writer has observed that when the 
rate of evaporation at 20, 40, and 60 feet to the lee- 
ward of a grove of black oak 15 to 20 feet high was 
11.5 c.e., 11.6 C.C., and 11.9 c.c., respectively, from a 
wet surface of 27 square inches, it was 14.5, 14.2 and 
14.7 c.c, at 280, 300 and 320 feet distant, or 24 per 
cent greater at the three outer stations than at the 
nearer ones. So, too, a scanty hedge-row produced 
observed differences in the rate of evaporation as fol- 
lows, during an interval of one hour : 

At 20 feet from the hedge-row the evaporation was 10.3 e.e. 
At 150 " " " *' " " " 12.5 c.e. 

At 300 '' " '' " '' '' " 13.4 c.c. 

Here the drying effect of the wind at 300 feet was 
30 per cent greater than at 20 feet, and 7 per cent 
greater than at 150 feet from the hedge. 

Then, too, when the air came across a clover field 
780 feet wide the observed rates of evaporation were : 

At 20 feet from clover 9.3 c.c. 

At 150 " '' " 12.1 c.c. 

At 300 " " " 13 c.c. 

Or 40 per cent greater at 300 feet away than at 20 feet, 
and 7.4 per cent greater than at 150 feet. 

The protective influence of grass lands, and the dis- 
advantage of ver}^ broad fields on these light lands, 
was further shown by the increasingly poorer stand of 
young clover as the eastern margin of these fields was 
approached, even when the drifting had been inappre- 
ciable. Below are given the number of clover plants 



170 Irrigation and Drainage 

per equal areas on three different farms as the distance 
to the eastward of the grass fields increased : No. 1, at 
50 feet, 574 plants; at 200 feet, 390 plants; at 400 feet, 
231 plants. No. 2, at 100 feet, 249 plants; at 200 feet, 
277 plants ; at 400 feet, 193 plants ; at 600 feet, 189 
plants ; at 800 feet, 138 plants ; and at 1,000 feet, 48 
plants. No. 3, at 50 feet, 1,130 plants; at 400 feet, 600 
plants; at 700 feet, 543 plants. 

In these cases the difference in stand appears to 
have resulted from an increasing drying action of the 
wind. On most of the fields, the destructive effects 
of the winds were very evident to the eye, and aug- 
mented as the distance from the windbreaks increased. 

It appears from these observations, and from the 
protection against drifting which is afforded by grass 
fields, hedgerows, and groves, that a system of rotation 
should be adopted, on such lands, which avoids broad, 
continuous fields. The fields should be laid out in nar- 
row lands, and alternate ones kept in clover or grass. 
Windbreaks of suitable trees must also have a beneficial 
effect upon the crops when maintained along fields, rail- 
roads, and wagon roads in such places as have been 
described, and especially in the prairie sections of the 
sub -h amid regions, where irrigation cannot be prac- 
ticed. It is, of course, true that trees on the margins 
of fields sap the soil in their immediate vicinity, and 
thus reduce the yield there ; but it seems more than 
probable that in open, windj^ sections their protective 
influence, which it has been shown they exert, will 
much more than compensate for this where there is a 
general deficiency of soil moisture. 



CHAPTER IV 

THE INCREASE IN YIELD DTE TO IRRIGATION IN 
HUMID CLIMATES 

In order to know liow important the right amount 
of soil moisture, applied at the right time, is, and in 
order to know whether it will pay to irrigate in humid 
climates, it is necessary to learn what yields are possi- 
ble under the best conditions when the crop must 
depend upon the natural rainfall, and, side by side 
with these in time and place, to measure the possible 
increase in yield due to irrigation, if any there be. 

When the study of the importance of soil moisture, 
and the principles underlying the methods of saving 
and utilizing it, were begun at the Wisconsin station 
in 1888, it very early became evident that, in order to 
learn just how important it is in plant culture to con- 
serve the soil moisture, some method must be adopted 
which would permit of giving to the plants under inves- 
tigation all the water they can use to advantage. 
This led to the series of experiments which have been 
recorded in the introductory chapter, aiming to meas- 
ure the amount of water which different cultivated 
plants can use under the conditions of field life. But 
when the results attained under the methods there used 
showed that such large yields are possible, it became 

(171) 



172 Irrigaiion and Drainage 

important to supplement the rainfall under wholly 
normal field conditions, to see if there would then be 
any notable increase over the yields produced under 
the natural field conditions. This led to a series of 
experiments to be conducted parallel with those on till- 
age, to learn how far short of possible yields our actual 
ones are when secured under the best moisture relations 
at our command ; and irrigation experiments as checks 
on our tillage experiments were begun, the results of 
which it is important to state. 

In conducting these control experiments on irriga- 
tion, the aim has been to treat the crop growing under 
the conditions of the normal rainfall and under those 
of the rainfall supplemented by irrigation, exactly 
alike in every way until it became apparent that more 
water might be used with advantage, when water was 
applied to the control plots as often as it seemed de- 
sirable. No other elements of difference have been 
introduced than those growing out of appljdng the 
additional water. 

IMPORTANCE OF THE AMOUNT AND DISTRIBUTION OF 

WATER IN POTATO CULTURE, AND THE ADVANTAGE 

OF IRRIGATION IN CLIMATES LIKE WISCONSIN 

There have been two seasons' woi'k with this crop, 1896 and 
1897, and both years the potatoes have been planted in rows 30 
inches apart and in hills 15 inches in the row, or else twice that 
distance. The ground in each case was given a good dressing of 
farmyard manure, plowed in 6 inches deep. Large tubers were 
nsed for seed, cut two eyes to the piece, and planted with hoe 
about 3 inches deep, and the ground harrowed after planting. 



Increase of Potato Croj) hy Irrigation 173 

The Rural New-Yorker has been the chief variety grown, but 
each year an unnamed variety of the Burbank type has been used 
to finish out the piece. 

The potatoes were planted about the middle of May each year, 




Fig. 26. 



Difference in yield between Rural New-Yorker potatoes, 
irrigated and not irrigated, in 1898. 




Fig. 27. Difference in yield between potatoes of Bnrbanli t5T)e irrigated 
and not irrigated, in 189G. 




Fig. 28. Difference in yield between Rural New-Yorker potatoes, 
irrigated and not irrigated, in 1897. 

and given flat cultivation after every rain, or oftener, until the 
vines were so large as nearly to cover the ground, when they were 
hilled with a double shovel plow drawn through the center of each 
row, forming ridges about 5 inches high, the nose of the shovel 
passing about 3 inches below the surface of the ground. 



174 



Irrigation and Drainage 



The amounts of rainfall and of water applied by irrigation are 
given in the table below : 





Rainfall . 




Water 


of irrigation- 


^ 




1896 


1897 




1896 




1897 




INCHES 


INCHES 




INCHES 


INCHES 


May... 


. 6.11 


.51 


May . . . 




May 


.... 


June . . . 


. 2.25 


4.03 


June. . . 




June 




July... 


. 3.42 


1.79 


July 10. 


.. 2.15 


July 20.... 


2.45 


Aug. . . 


. 2.43 


3.7 


July 21. 


.. 2.15 


Aug, 18 . . . 


2.45 


Sept... 


. 3.73 


1.73 


Aug. 3 . 
Aug. 10 
Sept. 3. 


.. 2.15 
.. 2.15 
.. 2.15 


Sept. 8 .... 


2.45 


Sum. 


17.94 


11.76 


10.75 


7.35 



The distribution of the rainfall during the season can be 
learned from the table given on page 108. It will be seen that in 
1896 the irrigated potatoes had 10.75 inches, and in 1897 7.35 
inches, more water than the potatoes grown under the natural 
rainfall conditions. "" 

These differences in the amount of water produced differences 
of yield, which are shown below in the table, and graphically to 
the eye in Figs. 26, 27 and 28. To eliminate the effects of varying 
soil conditions, the water was applied to alternate groups of 6 to 
10 rows, with corresponding intervening groups of rows which 
received no water. There were 16 of these plots in 1896 and 22 
in 1897, making 38 trials in all, in which there were grown a total 
of 555 bushels of potatoes, or 33,304.4 pounds. 

Table showing yield per acre of potatoes irrigated and not irrigated in 

Wisco7isin 

Rural New-Yorker 



1896 

1897 

1896 

1897 

Mean 

Difference 105.& 1.2 



Large 


Irrigated- 


Small 


' Not irrigated 

Large Small 


BU. 




BU, 


BU, BUo 


382 




12.2 


280.3 10.2 


365.8 




9.1 


239.6 9.7 


BuRBANK Type 




220 




22.7 


141.5 16.2 


302 




16.8 


184.9 19.75 


317.5 




15.2 


2ii.e 14 



Increase of Cabbage Croj) by Irrigation 175 

There is thus shown a difference of 105.9 bushels of merchant- 
able tubers per acre, as an average of two years, in favor of the 
larger water supply. 



EFFECT OF SUPPLEMENTING THE RAINFALL IN WIS- 
CONSIN FOR CABBAGE CULTURE 

In the work with cabbage, the rows were set 30 inches apart, 
and in half of the area the plants were set 15 inches apart in the 
row, and on the balance of the area 30 inches apart, of the variety 
Fottler's Drumhead. There were, in all, 22 alternating plots of 6 
rows each, one half irrigated and the balance not. The soil was 
a rather heavy clay loam, which had been heavily manured the 
previous year, and had grown a crop of cabbage and cauliflower, 
but nothing was added this season. Flat and frequent cultivation 
was given until the plants were large and nearly covered the ground, 
July 21, when the first irrigation was made, the irrigated rows 
being furrowed the same as the potatoes, and not again disturbed. 

The mean weight of heads produced under the two treatments 
was as follows : 

' Thin planting Thick planting > 

Irrigated Not irrig. Irrigated Not irrig. 

LBS. LBS. LBS. LBS. 

Firm heads 7.6 6.95 5.13 4.46 

Loose heads 4.88 4.33 3.23 2.39 



The weight of the heads dressed for market, computed for one 
acre, was as expressed in the following table: 

, Thin planting v Thick planting < 

Irrigated Not irrig. Diff. Irrigated Not irrig. Diff. 

LBS. LBS. LBS. LBS. LBS. LBS. 

Firm heads 30,610 29,480 1,130 46,590 40.100 6,490 

Loose heads 6,227 4,624 1,603 7,688 5,943 1,745 

Total 36,837 34,104 2,733 54,278 46^043 8,235 

Leaves and stumps.. 42,730 39,220 3,510 64,100 57,630 6,470 

Grand total.... 79,567 73,324 6,243 118,378 103,673 14,705 

Tons 39.78 36.66 3.12 59.19 51.84 7.35 



176 Irrigation and Drainage 

The amount of water given to this crop was 8.245 inches, in 
four applications, July 21, Aug. 3 and 10, and Sept. 3, 2.061 
inches being applied each time. 

The difference between equal numbers of rows of cabbage 
irrigated and not irrigated is shown in Fig. 29. Were the cabbage 
grown for green fall and early winter feed for stock it will be seen 
that the close setting gives a difference in favor of irrigation 




Fig. 29. Difference in yield between cabbage, irrigated and not irrigated. 

amounting to 7.35 tons per acre. This occurred, too, under con- 
ditions in which the plots not irrigated received considerable 
water from seepage from the heavy irrigation of a piece of 
meadow. 

The same season that these experiments were made with cab- 
bage, similar ones were conducted with mangold -wurzels and with 
turnips. But while a good yield of beets was secured per acre, 
namely, 15.7 tons, there was only 18 pounds difference, the six 
rows of irrigated mangolds yielding 5,100 pounds and those not 
irrigated 5,082 pounds. The turnips, on account of a blight, 
did nothing under either treatment, and the same was true foi 
rape. 

THE EFFECT OF SUPPLEMENTING THE RAINFALL WITH 
IRRIGATION ON THE YIELD OF CORN 

During four consecutive years we have grown corn upon one 
area, irrigating a part and reserving another part not irri- 
gated, as a check. The soil of this plot is medium clay loam. 



■Pxi 



Increase of Corn Croj) by Irrigation 



177 



rust before beginning the experiments it had been in clover, and 
was dressed with farmyard manure at the rate of 44 loads per acre 
before plowing, in the spring of 1894. Since this time it had re- 
ceived no manure or fertilizers of any kind, one object of the 
experiment being to ascertain whether under irrigation the land 
rapidly deteriorates in productiveness. 

Each season the corn has been planted very close, in rows 30 
inches apart and in hills 15 inches in the row, working upon the 
hypothesis that when an abundance of water is supplied more 
plants may be grown upon the same area, the hypothesis having 
been suggested by the large yields universally secured in the 
experimental cylinders. 

The number of stalks in a hill has varied, but usually as 
many as 3 to 5 stalks have been allowed to mature. Both flint 
and Pride of the North dent corn have been grown each year, 
and one season a part of the area was planted with rows 36 
instead of 30 inches apart. The table which follows gives the 
yields of water-free matter per acre, together with the rainfall of 
the growing season and water added by irrigation: 





Not Irrigated 


In 


igated 


Differ 


ence 


Kind 


Water 


Dry 


Water 


Dry 


Water 


Dry 


of corn 


used 


matter 


used 


matter 


used 


matter 




INCHES 


LBS. 


INCHES 


LBS. 


INCHES 


LBS. 


Flint 
Dent 


8.15 


7,916 
7,426 


16.76 


11,080 
9,625 


8.61 


3,164 
2,199 


Flint 
Dent 


4.48 


2,458 
3,144 


31.08 


10,048 
11,125 


26.6 


7,590 
7.981 


Flint 
Dent 


15.02 


8,129 
8,450 


27.07 


10,320 
10,280 


12.03 


2,191 
1,830 


Flint 
Dent 


10.66 


6,766 
6.853 


16.36 


8,571 
8,438 


5.7 


1,805 
1,585 



1894 
1895 
1896 
1897 



It will be seen, from the data of this table, that there has been 
during the four years a mean gain due to the increased water sup- 
ply amounting to 3,543 pounds of water-free substance, while the 
mean yield under the season's rainfall with the best of tillage has 
been 6,393 pounds per acre, or an increase of 55 per cent. The 
smallest mean gain realized in any year has been 24.9 per cent 
and the largest 278 per cent. 



178 



Irrigation and Drainage 



In Fig. 30 is shown the difference between tne corn on land 
irrigated and not irrigated in 1895, when there was the largest ob- 




Fig. 30. Difference in yield between maize, thickly seeded, irrigated 
and not irrigated, in a di-y season. 

served difference in the yield. Fig. 25 shows the difference where 
the rows are 44 inches apart instead of -'JO inches, as in the former 
case. 



THE EFFECT OF SUPPLEMENTING THE RAINFALLL WITH 
IRRIGATION ON THE YIELD OF CLOVER AND HAY 

The crop of hay is, perhaps, the one above all others among 
the general farm crops which may be made to respond most effec- 
tively to irrigation in humid climates. Indeed, it is the chief on- 
in Europe which has been grown by irrigation north of Ital 



Increase of Hay Crop hy Irrigation 179 

and southern l^'rance. Reference has already been made to 
water meadows. 

We have shown in another place that the average yield of hay 
per acre in thirteen states in this country was, for 1879, only 1.1 
tons. It is true, however, that good soils, well managed, may be 
made to yield most years an average of possibly 1.5 tons per acre. 
There will be seasons, however, for these soils when the yield will 
drop back to 1 ton per acre. Again, those seasons are rare for 
most soils in the United States which will permit them to produce 
three -fourths of a ton of hay per acre as a second crop without 
irrigation. 

Our experiments in irrigating clover for a second crop gave 
1.798 tons, 2.035 tons, and 1.773 tons of hay, containing 15 per 
cent of moisture, for the years 1895, 1896, and 1897 respectively. 
In irrigating the first crop of clover, the yields have been 4.01 tons 
per acre, in a case of sub -irrigation through tile drains in 1895, 
and 2.G71 and 2.65 tons in 1897, which were surface irrigated, 
making an average for the two crops of 4.979 tons of hay per acre 
so thoroughly cured as to contain 85 per cent of dry matter. 
These results, it should be understood, are derived by making an 
actual determination of the dry matter in each crop and comput- 
ing the weights of hay from the amount of dry matter. 

It will be observed that these yields are more than four times 
the mean yield of the thirteen states cited in another place. In 
addition to the first and second crops, there has been each time an 
excellent third crop, which could be used for fall pasture, and 
easily double in quantity the non- irrigated fall feed of the best 
seasons. Fig. 31 is a view of the second crop of 1895, the third 
crop on the same ground, giving pasture for 58 adult sheep 31 days 
on 3.2 acres. 

A CROP OF BARLEY AND A CROP OF HAY THE 
SAME SEASON 

In the spring of 1897 we seeded a piece of ground to clover 
rith barley, irrigating a part of the barley twice, both to see what 
le effect would be upon the yield of barley and upon the clover 



180 



Irrigation and Drainage 



which had been sown with it. It so happened that immediately- 
after each time of irrigating the barley a good rain followed, and 
the difference in yield of grain and straw per acre was small, as 
stated below: 



Air-dry straw— lbs. 
Air-dry grain — bu. 



Irrigated 


Not irrigated 


Difference 


5,735 


5,133 


G02 


45.67 


44.25 


1.42 



But the effect on the clover was very marked. In order to 
bring np tlie clover on the areas not irrigated, the ground was 




Fig. 31. Second crop of clover hay on iiTigated ground. 

irrigated immediately after cutting the barley, July 23. Two other 
irrigations were given the ground, and as a result there was a crop 
of mixed clover and barley, cut on Sept. 22, which equaled 1,36 
tons of hay. The barley cut with the clover resulted from the 
germination of seed which shelled in harvesting the grain, and 
was just heading out when it was cut to put into the silo. 

It is very evident, from these results, that it will be possible 



Increase of Small Fruit Crop bij Irrigation 181 

to seed clover with either oats or barley, and by cutting the first 
crop early for hay and then irrigating, a second crop of hay equal 
at least to one ton per acre may usually be taken, besides making 
it certain that a good stand of clover is secured for the next year. 

THE EFFECT OF SUPPLEMENTING THE RAINFALL FOR 

STRAWBERRIES 

The strawberry is a crop which will respond in a marked man- 
ner to judicious applications of water in most parts of the United 
States suited to its growth, as the results secured at this station 
by Professor Goff clearly show. His yields x>er acre were: 

Irrigated Not irrigated Difference 
BU. BU. BU. 

1894 214.6 109.3 105.3 

1895 272.9 32.2 240.7 

Mean 243.8 70.8 173 

It is here seen that the irrigated yield was more than three 
times as large as that under natural rainfall conditions ; and not 
only was the yield this much larger, but the quality of the berries 
was also improved by the irrigation, they being larger and more 
salable. 

While we are able to cite no critical data regarding the 
advantage of irrigation in humid climates on blackberries, rasp- 
berries, currants and gooseberries, the unquestioned fact that these 
do very frequently suffer severely from the effects of drought 
leaves no room to doubt that these, like the strawberries, would 
be greatly benefited by irrigation in very many seasons. 

CLOSER PLANTING MADE POSSIBLE BY IRRIGATION 

It has been pointed out that in sub -humid climates 
the limiting factor which determines the number of 
plants which may develop to advantage in a given soil 
is the amount of available moisture ; but that in coun- 



182 Irrigation and Drainage 

tries where there is an abundant and timely distribution 
of rain, or where irrigation is practiced, the number 
of plants per acre may be so far increased that the 
limiting factors become the available plant-food stored 
in the soil, the amount of sunshine which falls upon 
the area, or the circulation of air about the assimilat- 
ing foliage. 

It is very evident that were the amount of available 
water for crop production the only factor which de- 
termines the number of plants which can be grown per 
unit area, the methods of irrigation would make it pos- 
sible to greatly increase the yield of almost any crop 
in the most humid of climates. But there are many 
limiting factors which set rigid bounds beyond which 
irrigation may not pass. 

Sufficient hreathing room in the soil. — Since the roots 
of all cultivated plants demand free oxygen in the soil 
for their respiration, and since not only the possible 
quantity of free oxygen in the soil, but the rate at 
which it may be supplied, decreases as the quantity of 
water in the soil increases, and since the closer the 
plants are set upon the ground the more densely crowded 
must the roots be in the soil, and the more rapid must 
be the interchange of gases between the soil and the 
air above in order to meet the increased demands for 
growth, it is plain that the demand for free oxj^gen in 
the soil sets a rigid limit beyond which closer planting 
must not be pushed. 

It must be kept ever in mind that the soil is like a 
very poorly ventilated assembly hall, which may easily 
be so crowded as not only to produce discomfiture to 



Factors Limiting Closeness of Planting 183 

its occupants, but disaster as well. Nor do the roots 
of the plants which occupy the field constitute the only 
demand for free oxygen in the soil, for the various 
fermenting germs which transform humus into avail- 
able nitrates must have free oxygen, or the all- 
important nitric acid cannot be made, and the farm- 
yard manures applied to the soil must lie there unal- 
tered and of no avail. 

Soil temperature reduced hy too close planting. — Then, 
again, too heavy verdure above the soil so completely 
absorbs the heat from the surrounding air and dissi- 
pates it again into space, that the soil temperature can- 
not rise high enough to produce the maximum rate 
of solution and production of plant -food, nor the 
maximum root pressure so essential to sending the dis- 
solved and prepared food into the foliage above, where 
assimilation takes place ; while the humus and ma- 
nure-fermenting germs themselves must work the slower 
the lower the soil temperature is after it falls below 
98° F. It is true that available nitrates may be applied 
to the soil direct, and other of the ash ingredients in 
soluble form may be added, or the soil may receive 
thorough and repeated tillage before the crop is put 
upon it, and thus a supply in advance be generated, 
which leaves more of the oxygen and of the soil warmth 
for the service of the roots; but neither of these con- 
ditions can be attained except at added cost. 

The sunshine itself is limited. — Even when we come 
to the item of sunshine itself, it is easy to so increase 
the number of plants that not enough sunshine can be 
absorbed to produce normal growth, and a diminished 



184 Irrigation and Drainage 

yield or inferior quality results. The taller the plauts 
which are brought togethe-r, the farther apart as a 
rule must they be placed, in order that sufficient sun- 
light for the best results can be had. The flint varie- 
ties of maize are readily grown closer together than the 
smaller of the dent varieties, and these, in their turn, 
may stand closer on the ground than the large southern 
varieties. 

Neither the starches nor the cellulose out of which 
plant tissues are built can be properly organized and 
laid down in too feeble a light, for its actinic power is 
demanded to accomplish this work, just as it is in pho- 
tography. When it is remembered that an instanta- 
neous exposure of a plate in the bright sunshine may 
accomplish more chemical change in the negative than 
can be done in two minutes in the diffused light of a 
well-lighted room, it can be readily understood that the 
work of assimilation in the lower leaves in close plant- 
ing must be greatly enfeebled. 

It is for this reason, apparently, that ears will not 
form on stalks of maize planted too closely, and that 
they form, more abundantly in closer planting on the 
small, low varieties than on those which are taller. 

It is for the same reason, too, that too closely 
planted crops of almost any kind have weak stems and 
are unable to stand up well, often lodging ; neither the 
starches for the kernels, in the former case, nor the 
cellulose in the latter for the building of the frame- 
work, are able to form rapidly, and abnormal growth 
is the result. Whoever has entered and emerged from 
a tunnel has been surprised at the short distance from 



I 



Factors Limiting Closeness of Planting 185 

the nioutli at which the tunnel becomes dark ; the re- 
peated reflections from the walls soon absorb completely 
all of the light which enters. It is the same way with 
close planting, especially if the individuals are tall, the 
upper parts of the tall plants absorbing just as 
much light as the same length of shorter plants, hence 
leaving less light to work in the foliage and stems of 
the lower parts. 

Possible insiifficiencii of carbon dioxide in close 
planting. — When a crop like maize, which grows so 
tall and spreads its leaves so broadly, is planted closelj^ 
it seems not impossible that on days of exceptionally 
bright sunshine and when very little wind is moving, 
there may be such rapid consumption of carbon dioxide 
from the air as to so far reduce its amount that an 
inadequate supply may actually reach the plants. 

It has been shown on a preceding page that a clover 
crop 3'ielding 4,500 pounds of hay per acre demands 
for its carbon all of the carbon dioxide contained in a 
layer of uniform density covering the acre 3,503 feet 
deep. But in the case of a corn crop, in which the yield 
of water -free matter has exceeded 14,000 pounds, the 
volume of air required to give up its carbon dioxide 
must have exceeded that above more than threefold, 
or a column of uniform density exceeding 10,509 feet 
in height. Fully 80 per cent of this assimilation of 
carbon by the corn plant must take place in the 50 
days following July 1. Imagine, if you will, a field of 
corn 160 rods long and 1 rod wide, enclosed by a 
transparent structure having the same floor space and 
rising to a height of 10,000 feet, so as to enclose the 



186 Irrigation and Drainage 

volume of air stated above. Now, let this structure be 
provided with a ceiling without weight, which is lifted 
as the corn grows in height. This imaginary ceiling is 
to separate the volume of air stored above from the 
moving air in the corn field below, and to admit 
through a changing doorway a steady stream whose 
cross -section is that of the transverse section of the 
room occupied by the corn. How rapidly must this 
stream of air flow in order to discharge 80 per cent of 
the volume contained in the structure in the sunshine 
hours of 50 days ? The maximum number of sunshine 
hours in the latitude of New York is about 623. If we 
suppose the corn to be 1 foot high July 1 and 10 feet 
high on August 19, the ceiling to have risen uniformly 
in the meantime, so that the stream of air increased in 
depth from 1 foot to 10 feet ; then, taking the mean 
depth of the moving air current at 5.5 feet, its hourly 
velocity, in order to convey the 80 per cent of air 
across the field, must have been 1.167 miles. On the 
other hand, let us suppose the corn field to be square, 
so that the area is as compact as possible, so that a 
stream of air now about 13 rods wide instead of 1 is 
passing across it. The required velocity to convey the 
80 per cent of air across the field is now only one- 
ninth of a mile per hour and less than 10 feet per 
second. Since the yield of dry matter per acre is the 
largest we have yet raised under field conditions, and 
the computed velocities above are so small, it does not 
appear likely that an insufficiency of carbon dioxide in 
the air can ever be a serious limiting factor to the 
closeness of planting when irrigation is practiced. 



Maximum Limit of Productiveness for Maize 187 



MAXIMUM LIMIT OF PRODUCTIVENESS FOR MAIZE 

In order that some idea of the possible maximum yields of 
maize per acre might be formed, we have gone into the fields 
when the corn was mature, and selected 40 of the largest stalks 
bearing the largest ears we could find, and have determined the 
water-free matter in both ears and stalks, in order to secure a 
measure of the mean maximum adult plant to use as a basis of 
computation for this problem. The results were these: 

40 stalks of Pride of the North maize contained 15.6 lbs. water-free substance. 

40 ears " " " " " " 16.1 " 

40 " " " " " " " 13.7 " shelled corn. 

40 " " " " " " " 2.4 " cobs. 

Using these data, we may compute the maximum possible 
yields per acre where different degrees of closeness of planting are 
adopted, supposing that every plant produces a maximum-sized 
stalk, bearing a maximum ear corresponding with the data above. 

Then maize planted in hills 4 feet x 4 feet, and 4 stalks in a 
hill, or in drills 4 feet x 1 foot, might yield 8,630 pounds dry mat- 
ter, 3,730 pounds kiln-dried shell corn, equal to 66.61 bushels, or 
73.27 bushels when containing 10 per cent of moisture. 

With maize planted in hills 44 inches x 44 inches, 4 stalks in 
a hill, or 44 inches x 11 inches in drills, the maximum yield per 
acre would be 10,270 pounds dry matter, 4,439 pounds kiln-dried 
shelled corn, equal to 79.27 bushels, or 87.2 when containing 10 
per cent of moisture. 

Maize planted 42 inches x 42 inches, 4 stalks in a hill, or in 
drills 42 inches x 10.5 inches, might yield 11,270 pounds of water- 
free matter and 4,871 pounds of kiln-dried shelled corn, equal to 
87 bushels, or to 95.7 bushels when containing 10 per cent of 
moisture. 

Maize planted 36 inches x 36 inches, 4 stalks in a hill, or in 
drills 36 inches x9 inches, might yield 15,340 pounds of dry matter 
and 6,600 pounds of kiln-dried shelled corn, equal to 118.4 
bushels, or to 130.27 bushels when containing 10 per cent of water. 



188 Irrigation and Drainage 

Maize planted 30 inches x 30 inches, 4 stalks in a hill, or 30 
inches x 7.5 inches in drills, might yield 22,090 pounds of dry 
matter per acre and 9,574 pounds of kiln-dried shelled corn, 
equal to 170.4 bushels, or 187.44 bushels containing ]0 per cent 
of water. 

Maize planted 30 inches x 15 inches, 4 stalks in a hill, or in 
drills 30 inches x 3% inches, might yield, if every stalk equaled the 
average of the 40 stalks cited above, 44,180 pounds of dry matter 
per acre and 19,148 pounds of kiln-dried shelled corn, equal to 
340.8 bushels, or 374.88 bushels when containing 10 per cent of 
moisture. 

Some of the yields here computed have been realized under 
field conditions, but the higher ones never have been and prob- 
ably never can be, under any system of culture as a single crop. 
In our experimental work with the large cylinders, the largest 
yield we have obtained was 34,730 pounds of water-free sub- 
stance when 4 stalks occupied a soil space of 1.767 square feet, 
which is closer planting than the closest given above, namely 
rows 30 inches apart, with corn in drills, stalks \% inches apart. 

The largest yield we have secured in the field was on an 
area of irrigated ground measuring about 2,400 square feet, where 
the amount of dry matter per acre was 29,000 pounds, or 14.5 
tons. In this case, the corn was planted in rows 30 inches apart 
and in hills 15 inches apart, with 3 to 5 stalks in a hill. The area 
was not an isolated plot, but was a selected spot in an irrigated 
area where, on account of a sag in the ground, the corn had 
received more than the average amount of water. The closeness 
of planting in this case was equivalent to drilled rows with 1 stalk 
every 3% inches, which is the same as the closest given above, 
but the corn was a variety of flint maize, not dent. 

THE OBSERVED YIELDS OF MAIZE PER ACRE PLANTED 

IN DIFFERENT DEGREES OF THICKNESS AND WITH 

DIFFERENT AMOUNTS OF WATER 

It has been possible, with our irrigation, to make a direct test 
of the influence of the amount of water on closeness of planting 



Maximum Limit of Production for Maize 189 

maize, and thus to demonstrate whether, with the aid of irriga- 
tion, it will be possible in humid climates to secure larger yields 
by planting closer together. 

The problem this year has been tested with two varieties of 
maize. Pride of the North, and a white dent of unknown name. 
Each has been planted in rows 44 inches apart and in hills 15 
inches in the row. The white dent was thinned to 4 stalks, 3 
stalks, 2 stalks, and 1 stalk in a hill, and the Pride of the North 
to 3 stalks, 2 stalks, and 1 stalk in a hill. It was found, after the 
stalks had attained some size after thinning, that the white dent 
threw out 1 and sometimes 2 suckers where it had been thinned 
to 1 stalk. These were allowed to stand, rather than incur the 
risk of introducing greater irregularities which would be unknown. 
But few of these suckers matured ears, and hence their effect has 
been to increase the amount of stalk in proportion to the ear, and 
possibly even to reduce the weight of ears, particularly on the 
ground not irrigated. The Pride of the North was planted on 
ground from which hay had been cut three consecutive years, and 
in which a fair amount of clover was maintained, the land having 
been irrigated. The white dent was grown upon ground from 
which two crops of cabbage had been taken, and which had been 
irrigated for both crops. Preparatory to planting the first crop of 
cabbage, after turning under the clover sod, the ground had been 
given a dressing of partly rotted stable manure amounting to 68 
tons per acre. In addition to this, a mixture of commercial fer- 
tilizers consisting of 157 pounds of bone meal, 25 pounds Armour's 
"all soluble" fertilizer and 6 pounds of nitrate of soda was sown 
broadcast upon the ground Aug. 16. Neither manure nor fertil- 
izers of any kind were given to the soil of either piece for the 
season the corn was grown nor the year before. 

In both cases the corn was harrowed before coming up, and 
cultivated twice in a row until too large to ivork longer. The 
several areas bearing corn of different degrees of thickness were 
divided into three sub-plots, and the middle one in each case was 
not irrigated, while the two adjacent ones were. 

At maturity the corn was husked, and the amount of water- 
free substance in both ear and stalk determined in each case. 



190 



Irrigation and Drainage 



The photo- engravings, Figs. 32, 33, 34 and 35 (pages 192, 193), 
stow the relative amounts of corn husked from each plot and the 
areas upon which these were grown, while in the table below are 
given the yields per acre: 

White Dent 



< 4 stalks 


, 3 stalks . . 2 stalks ■ 


. 1 stalk < 


Dry 
matter 


Shelled 


Dry 

matter 


Dry 
Shelled matter 


Shelled 


Dry 
matter 


Shelled 


per acre 


corn 


per acre 


corn per acre 


corn 


per acre 


corn 


LBS. 


BU. 


LBS. 


BU. LBS. 
Corn Irrigated 


BU. 


LBS. 


BU. 


11,426 


53.44 


12,567 


63.23 11,712 


66.01 


9,554 


49.53 



Corn not Irrigated 
8,758 30.38 9,126 39.45 7.931 48.66 7,354 39.03 

Difference in Yield 
2,668 23.06 3,441 23.78 3,181 17.35 2,200 10.5 

In the case of the Pride of the North, the corn was planted 
3 stalks, 2 stalks, and 1 stalk in a hill, and the yields in this case 
were as follows : 

Pride of the North Dent 



Dry matter 


Shelled 


Dry matter Shelled 


/- J. hiai 
Dry matter 


K. V 

Shelled 


per acre 


corn 


per acre corn 


per acre 


corn 


LBS, 


BU. 


LBS. BU. 

Corn Irrigated 


LBS. 


BU. 


12,300 


73.24 


11.350 69.62 
Corn not Irrigated 


8,944 


55.29 


10,265 


45.20 


9,328 47.79 
Difference 


8,536 


52.65 


2.035 


28.04 


2,022 21.83 


408 


3.64 



It will be seen from these tables that the yield of water-free 
substance per acre was largest in every case where the corn was 
planted 3 stalks in a hill every 15 inches, and in rows 44 inches 
apart. It is a significent fact that this is true, not only with both 



Yields of Maize tvith Irrigation 191 

varieties of corn, but. also where the corn was irrigated and where 
it was not irrigated. It will be seen, further, that the smallest 
yield of dry matter per acre was produced where the smallest 
amount of seed was used, namely, where 1 stalk grew every 15 
inches ; but one-third the number of plants produced about three- 
fourths as much dry matter per acre as did the larger number of 
plants. 

It must be understood, however, that so far as mere water 
is concerned, the thinnest planting had decidedly the advantage, 
as no effort was made, even on the ground irrigated, to make 
the water applied proportional to the number of plants and, there- 
fore, to the evaporating surface. Whether making the amount 
of water proportional to the number of plants would have materi- 
ally increased the yields of the ithicker seeding, is a problem 
which awaits demonstration. Indeed, we do not, as yet, know 
that the thinnest seeding had all of the water which could be used 
to advantage, even where irrigation was practiced. But the fact 
that the smaller variety of maize. Pride of the North, the one 
which produced no suckers, and, therefore, the one which more 
nearly represented 1 stalk every 15 inches, only gave an increase 
of 408 pounds of dry matter per acre for the 7.642 inches of water 
added by irrigation to the rainfall of 10.06 inches, appears to show 
that this corn found in the 10.66 inches of rain nearly all the 
water it could use to advantage. This view is strengthened, 
also, by the fact that the theoretical yield of dry matter per 
acre for the maize, computed from the data in the table on 
page 187, is 8,848 pounds, only 312 pounds more than was 
observed. 

Looking at the yield of kiln-dried shelled corn per acre, it 
will be seen that here a somewhat different relation holds, the 
largest crop with the white dent variety being secured from 2 
stalks in a hill every 15 inches ; but with the smaller variety of 
Pride of the North the largest yield of shelled corn coincided 
with the 3 stalks in a hill where irrigation was practiced ; but 
where the natural rainfall alone produced the crop, the largest 
yield was associated with the thinnest seeding, or 1 stalk every 
15 inches in the row. It is a noteworthy fact, too, that the 7.642 



192 



Irrigation and Drainage 



inches of water added by irrigation only increased the grain yield 
3.64 bushels per acre on the thinnest seeding, appearing to show 








Fig. 32. Maize, irrigated and not irrigated, four stalks in a hill, 
middle section not irrigated. 

that for this soil and rainfall there was very nearly the right num- 
ber of plants in the row. 






^ji 




-iimMM' ^^4:m:^Mli%d #^4" 




Fig. 33. Maize, irrigated and not irrigated, three stalks in a hill, 
middle section not irrigated. 

In regard to the yields from the thicker seeding, it must be 
said that it does not follow from the experiments that they might 
not have been quite different if, in the application of water to the 
several plots, the amounts had been made proportional to the 
number of plants growing on the area ; for it may fairly be pre- 



Influence of Thick Seeding on Development 193 

sumed, until positive demonstration shall prove to the contrary, 
that in case there was a deficiency of soil moisture for the thick 







WfW&k 



Fig. 34. Maize, irrigated and not irrigated, two stalks in a hill, 
middle section not irrigated. 

seeding, a larger supply would have increased the yield of shelled 
corn as well as the total amount of dry matter. 








<^L«i]^ 



."«^«a*jc1^SaJ1^^5 ^^ 



m\ 



Fig. 35. Maize. Irrigated and not irrigated, one stalk in a liill, 
middle section not irrigated. 



INFLUENCE OF THICK SEEDING AND IRRIGATION ON 
THE DEVELOPMENT OF THE PLANT 

It was observed, the first year the maize was planted thickly 
and irrigated, that the corn did not appear to develop quite nor- 



M 



194 Irrigation and Drainage 

mally, the tassels coming into bloom before the silks were ready to 
receive the pollen, and it looked then as though the failure to 
develop the normal amount of ears might result from this ab- 
normal development, in time, of the staminate and pistillate 
flowers. 

The facts are that very few kernels at all formed on the non- 
irrigated dent variety, and only imperfect ears matured on the 
flint variety ; while on the irrigated plots very many ears never 
filled at all, and with many of those which did develop ears, the 
kernels did not cover the entire cob, it being very often observed 
that no kernels at all formed at the butt of the ear, and sometimes 
none even half way to the tip. Whether the thick seeding and 
rapid growth stimulated by irrigation retards the development of 
the ear by shading, or overstimulates the maturing of the tassel 
so as to interfere with the proper fertilization, cannot be decided 
from data yet at hand, although the appearance of the plants 
looks very much as though such an abnormal development had 
been brought about. 

The nodes of the stalks are certainly lengthened by the close 
planting and irrigation practiced, but not all are equally affected. 
If it is true that a certain intensity of sunlight is required for the 
proper maturing of the ear, it might be anticipated that the effect 
of the shading would stimulate a greater elongation of the lower 
than of the upper nodes of the stem, thus placing the ear in more 
intense light. To ascertain whether any such change as this had 
occurred, measurements were made of 40 stalks of irrigated thick 
planting, and a corresponding number of plants not so closely 
planted and not irrigated, of Pride of the North dent, with the 
result that in the non- irrigated corn the height of the axil bear- 
ing the ear was 46.82 per cent of the height from the ground to 
the base of the tassel ; while that of the irrigated corn was 55.2 
per cent of the height. That is to say, the ear axil in the thickly 
planted irrigated corn was raised 8.38 per cent nearer to the 
tassel. 

In a second set of measurements, with the same variety of 
corn, the height of the axil bearing the ear was 49.44 per cent of 
the height of the tassel above the ground, while under the condi- 



Influence of Thick Seeding on Development 195 

tions of irrigation the height of the axil was 56.94 per cent of the 
height of the tassel, making a difference in this ease of 7.5 per 
cent in the same direction. In the case of a variety of flint corn, 
however, the conditions are the reverse of those just cited, the axil 
bearing the ear being 41.16 per cent of the height of the tassel, 
while on the ground irrigated this height is 39.59 per cent of the 
height of the tassel above the ground. The case is, therefore, not 
without exception as tending to show that the deficiency of light 
modifies the plant in the manner pointed out. 



CHAPTER V 

THE AMOUNT AND MEASUREMENT OF WATER REQUIRED 

FOR IRRIGATION 

There is no problem of greater or more fundamen- 
tal importance to the irrigator than that which deals 
with the amount of water required to produce paying 
yields when correctly and economically handled in the 
production of crops of various kinds. The problem is 
an extremely complex one, which has received as yet 
very inadequate systematic study on a rational basis, 
such as the exigencies of the case demand. 



THE MAXIMUM DUTY OF WATER IN CROP 
PRODUCTION 



i 



A given quantity of water applied to the soil, either 
in the form of rain or by methods of irrigation, renders 
its greatest service when the whole of it is taken up by 
the roots of the crop growing upon the ground, leaving 
none to be lost by surface evaporation or by percolation, 
unless, indeed, some soil leaching is indispensable to 
unimpaired fertility. Were it practicable to establish 
and maintain field conditions of culture which would 
insure that all water lost from the soil should take 

(196) 



The Duty of Water 197 

place through the foliage of the crop being fed, then a 
very small rainfall during the growing season, and a 
very small amount of water added by irrigation, would 
suffice for the production of large yields. 

In other words, the duty of water in crop produc- 
tion is determined by the necessary losses : (1) by 
transpiration through the plant ; (2) by surface evapo- 
ration from the soil; and (3) by surface and under- 
drainage. The more these sources of loss may be cur- 
tailed, the larger will be the duty of water in both arid 
and humid regions. 

In countries where irrigation must be practiced in 
order to successfully grow crops, skillful management 
may almost wholly prevent loss by drainage, and loss 
by surface evaporation from the soil can be made 
relatively very small, so that the major loss may 
be that which is transpired through the plant itself. 
So, too, in humid climates, the losses during the grow- 
ing season by both drainage and surface evaporation 
may be greatly reduced through skillful, intelligent 
practice. 

It will, therefore, be helpful, in forming an estimate 
of the possible duty of water, to use the data already 
presented in another place to compute the minimum 
number of acre -inches of water which may be made to 
produce yields of different amounts under the condi- 
tions where no drainage takes place, and where surface 
evaporation is made as small as it can well be. The 
results of such a calculation are given in the table 
which follows: 



198 



Irrigation and Drainage 



Table showing the highest probable duty of water for different yields per acre 

of different crops 



Bushels per acre . . 


15 


20 


30 


40 


50 60 

1 


70 


80 


100 


200 


300 


400 


Name of crop 


Least number of acre-inches of water 


"WTieat 


4.5 

3.21 

2.35 

2.52 


6 

4.28 

3.13 

3.36 

.41 


9 

6.42 

5.70 

5.04 

.62 


12 
8.56 
6.27 
6.72 

.83 


15 
10.7 

7.84 

8.4 

1.03 


18 
12.84 














Barley 


14.98 




15.68 

16.77 

2.07 


4.14 


6.2 




Oats 

Maize 


9.40 

10.08 

1.24 


10.98 12.54 

11.75 13.43 

1.45 1.65 




Potatoes 


3.27 






1 




Tons per acre 


1 


2 


3 


4 


6 


8 


10 


12 


14 


16 


18 


20 




Least number of acre-inches of water 


Clover hay, 

15 per cent water 
Corn with ears, 

15 percent water. 
Corn silage, 

70 per cent water. 


4.43 

2.08 
1.41 


8.85 
4.16 

2.82 


13.28 
6.24 
4.23 


17.7 
8.32 
5.64 


26.55 

12.47 

8.46 


35.4 

16.61 

11.28 


44.25 
20.72 
14.1 


24.95 
16.92 


29.1 
19.74 


33.26 
22.56 


37.42 
25.38 


41.58 

28.2 



This table must be regarded as showing the mini- 
mum amounts of water which will bring the crops 
named to full maturity so as to produce the jdelds speci- 
fied under conditions of absolutely no loss by surface 
or under -drainage, and where the evaporation from the 
soil itself is as small as it can well be. It must be 
further understood that the soil at seeding time already 
possesses the needful amount of water for the best con- 
ditions, and that at the end of the growing season it is 
yet so moist that no check to vigorous, normal growth 
has occurred. 

The figures in the table may, therefore, be regarded 



Conditions Modifying the Duty of Water 199 

as the nearest estimate now attainable of the minimum 
amount of water the irrigator can hope to deliver to his 
field where the yields there stated are expected ; and if 
there are necessary losses in bringing the water to the 
field, either by seepage or evaporation from the main or 
lateral ditches, or if the water is badly handled, so that 
there is a large amount of percolation ; or, again, if 
unnecessary losses occur through lack of proper tillage 
after irrigation, then the amounts stated in the table 
must be exceeded by the amount of these losses. 

CONDITIONS WHICH MODIFY THE AMOUNT OF WATER 
REQUIRED IN IRRIGATION 

Among the many factors and conditions which increase or 
diminish the duty of water may be mentioned: 

1. The peculiarities of the crop grown. — From what has been 
said regarding the amount of water required for a pound of dry 
matter and for yields of different amounts for different crops, it 
will be evident that both the amount of water required by a 
given crop and the frequency with which it should be applied will 
depend much upon the crop being grown. 

This variation in the amount of water required by different 
crops depends upon many factors, some of which are not well 
understood. Both the number and size of the breathing pores of 
the green parts of the plant, through which the air enters and 
from which the moisture escapes, may be expected to play an 
important part in determining the necessary loss of water which 
takes place. So, too, will the character of the foliage and the 
habit of the plant as influencing the amount of wind movement, 
and of shade over the soil of the field, effect the necessary loss 
of water from the soil. 

In illustration of the influence of the shade offered by the 
crop upon the loss of water from the soil may be cited the differ- 



200 IrrigaHon and Drainage 

ence in the amount of water in the soil of a potato field where 
the rows extended east and west, thus producing a shade on 
the north side of each row. The samples of soil were taken 
June 27. In this ease the rows were planted 3 feet apart, and 
the table given on page 161 shows a difference of 4.5 per 
cent in the upper six inches on the sunny and shaded sides of 
the row. 

Then, too, if the roots of the crop do not penetrate deeply 
into the soil, more water will be required, for the double reason 
that more water is liable to be lost by percolation below the root 
zone, and because a greater frequency of water will be required 
than if the roots went deeper ; hence, there will be more loss by 
surface evaporation. 

2. The character of the soil. — In the studies which have been 
made regarding the amount of water required for a pound of dry 
matter, there has been nothing to indicate that a plant growing 
in one soil requires more water than when growing in another, 
provided there is always an abundance of plant-food available to 
the crop throughout its period of growth. In other words, if it 
were possible to avoid losses by seepage, and by evaporation 
other than that which takes place through the growing crop, it 
does not appear that the duty of water would vary with the 
character of the soil. 

But, while it is true that by skillful management water may 
be distributed, even over the soils of coarse texture, with 
little or no waste through seepage, and while surface evaporation 
may be very greatly reduced by suitable methods of applying the 
water and of tillage, there will always be those living under the 
same water supply who are less skillful than others, and who will, 
by their lack of skill, require more water in order to secure the 
same yields ; and, in consequence of this, the duty of water will 
vary to some extent with the soil. 

There are really wide variations in the effectiveness of 
mulches developed from different soils, and while these are not 
as great as the variations in the rates of seepage, the losses of 
water through surface evaporation are less completely under con- 
trol than those due to percolation. The force of these statements 



Conditions Modifying Duty of Water 201 

will be more readily appreciated after a study of the results 
given in the following table : 

*Table showing the difference between the effectiveness of mulches developed from 

different kinds of soil 

< — Loss of water per 100 days — > 

Mulch Mulch Mulch Mulch 

Black marsh soil: No mulch 1-in. deep 2-in. deep 3-in. deep 4-in. deep 

Tons per acre 588 355 270 256.4 252.5 

Inches of water 5.193 3.12 2.384 2.265 2.23 

Per cent saved by mulches 39.54 54.08 56.39 57.06 

Sandy loam : 

Tons per acre 741.5 373.7 339.3 287.5 335.4 

Inches of water 6.548 3.3 2.996 2.539 2.785 

Per cent saved by mulches 49.6 54.24 61.22 57.47 

Virgin clay loam : 

Tons per acre 2,414 1,260 979.7 889.2 883.9 

Inches of water 21.31 11.13 8.652 7.852 7805 

Per cent saved by mulches 47.76 59.38 63.13 63.34 

The results in this table were secured by filling cylinders of 
galvanized iron, having a depth of 22 inches and a cross-section 
of -fjT of a square foot, with the soil named, by thorough tamp- 
ing, and then removing a depth of these soils equal to 1, 2, 3 
and 4 inches, returning enough of each kind in a loose, crumbled 
condition to fill the cylinders again level full, thus forming 
mulches of the respective depths. Under these conditions, the 
soils were exposed in the open field during 42 days to the normal 
atmospheric conditions, except that during times of rain the 
cylinders were covered. Water was added every 10 days to the 
reservoirs shown in Fig. 36, bringing the lowered surface back 
to a standard level. 

It will be seen that while the black marsh soil lost water 
through the unmulched surface at the rate of 5.88 tons per acre 
per day, the sandy loam lost water at the rate of 7.42 tons, 
and the virgin clay loam at the rate of 24.14 tons per acre per 
day, the latter exceeding the two former more than three- and 
four-fold. And, then, when the losses through mulches of cor- 
responding depths are compared, it will be seen that although 



♦Fifteenth Ann. Rept. Wis. Agr. Expt. Station, page 137. 



202 



Irrigation and Drainage 



these are much less than through the undisturbed soil, yet the 
relative differences are nearly as large. That is to say, the soil 
which, in the firm condition, has brought the largest amount of 
water to the surface, has also, when its surface 1, 2, 3 or 4 

V ^ 



y 



s 



s 



Fig. 36. Method of measuring effectiveness of mulches. 

inches were converted into a mulch, permitted the largest losses 
to take place ; while the soil having the slowest rate of loss 
when the surface was firm has also given the least evaporation 
through the several depths of mulches. 

If the losses per 100 days, expressed in inches, are brought 
into contrast, they stand as shown below: 





No mulch 


1-inch 
mulch 


2-inch 
mulch 


3-inch 
mulch 


4-inch 
mulch 




INCHES 


INCHES 


INCHES 


INCHES 


INCHES 


Virgin clay loam .... 


21 31 


11.13 
3.12 


8.65 
2.38 

6.27 


7.85 
2.27 

5.58 


7.81 


Black marsh soil 


5.19 


2.23 








Difference 


16.12 


8.01 


5.58 



It will be seen from this table that very wide differences 
exist between the losses of moisture through mulches of like 



Conditions Modifying Duty of Water 203 

depth, when developed from soils of different textures, and it is 
plain that with equal losses by percolation from the three soils 
here under consideration, more water would be required to bring 
a crop to maturity on the virgin clay loam than on either of the 
other soils, and hence, that the duty of water would be less, 
supposing, of course, that the three soils were equally fertile. 

Where water is plentiful and is being used freely, and es- 
pecially where irrigation by flooding is being practiced, the soils 
having the coarsest, most open texture will waste the most water 
by percolation through the zone of root feeding. Hence on this 
account the duty of water would be smaller on these soils than 
on those having finer texture. But, on the other hand, the sur- 
face evaporation from the closer soils is so much greater than 
from the sandy soils that the duty of water is much more nearly 
equal on them than it could be were it not for these opposite 
characteristics. 

Bearing upon this point E. Perels,* citing Eduard Markus, 
gives the results of observations covering three years in northern 
Italy on different kinds of soils and with different crops, from 
which it appears that rice, meadows and field crops use water in 
the ratio of 7 to 3 to 1, respectively, and when field crops are 
grown upon very heavy soil, heavy soil, medium soil, or light 
soil, they take water in the ratio of — 

Very heavy soil Heavy soil Medium soil Light soil 
100 . . to . . 115 . . to . . 168 . . to . . 230 

It is quite probable, however, that these ratios represent the 
relations of the degree of permeability of these soils under the 
conditions of the district, rather than the necessary amounts of 
water required for irrigation on these soils, where simply the 
transpiration from the crops and the evaporation from the soils 
is considered. In the cases of the rice and meadows, it is cer- 
tain that large percolation or surface drainage must have occurred. 

The losses of water by seepage from canals and reservoirs 



*Landwirthschaftlicher Wasserbau, p. 501. 



204 Irrigation and Drainage 

and the various distributaries will, of course, be relatively greater 
in regions of soils of coarse texture than where the soils are finer, 
so that here is a factor modifying the duty of water as con- 
sidered from the standpoint of the water company and irrigation 
engineer especially, but also with the large irrigator, who has 
extensive distributaries, through which the water must be con- 
veyed before it is finally taken out upon the land. It should be 
emphasized that our discussion has reference to the duty of water 
after it has reached the field where it is used. 

If it shall be found true that the continued growth of large 
crops upon a piece of land, and the consequent more complete 
evaporation of all water brought to the soil, thus curtailing the 
drainage, tends to develop alkalies to an injurious extent, or 
other prejudicial salts, so that flooding or leaching by irrigation 
shall be found necessary in order to restore fertility, then here, 
again, the character of the soil will modify the amount of water 
required. 

3. The character of the rainfall will necessarily modify in a 
marked manner the amount of additional water which may be 
used to advantage in the production of crops. It has already 
been pointed out on page 103 that the difference in the character 
of the rainfall in parts of California, Oregon and Washington, as 
compared with that of western Kansas and Nebraska, may explain 
why equivalent amounts of rain are much more effective in the 
former than in the latter regions, and if it is true that the fre- 
quent summer rains east of the Rocky Mountains do tend to hold 
the development of the roots of crops closer to the surface, and 
also to destroy the effectiveness of soil mulches, it is clear that 
the duty of water in climates where most of the growing season 
is an uninterrupted rainless period will be relatively higher than 
where frequent but inefficient showers tend to reduce the effi- 
ciency of mulches, and to hold the roots of crops closer to the 
surface. It is, therefore, likely to be found true that more water 
will be required for like results in western Texas, Oklahoma, 
Kansas, Nebraska, and the Dakotas, and similar climates, than 
will be required where the whole summer season is one con- 
tinuous interval of no rain. 



Conditions Modifying Duty of Water 205 

In still more humid climates, but where there are frequent 
recurrences of intervals of drought, the amount of water which 
must be used in order to secure full yields will be relatively 
'larger than would be required in rainless countries, because the 
surface losses of moisture will be relatively greater, as well as 
those from percolation and drainage. 

4. The character of the subsoil, as well as that of the surface 
soil, is an important factor in determining the duty of water, 
especially in the hands of the unskillful irrigator, and par- 
ticularly so if he possesses no knowledge, or exerijises poor 
judgment, regarding the water-holding power of the soil to 
which the water is being applied. Where the texture of the 
subsoil is coarse and its water -holding power small, it requires 
the best of judgment, both in regard to the amount of water 
which may be applied at one time and as to the rate at which it 
should be led over the surface or along the furrows, in order 
that there shall be no waste by percolation below the depth of 
root feeding. 

It has been pointed out that even moderately fine sands 8 
feet above the ground water quickly lose by percolation all but 4 
per cent, or less, of their dry weight, of the water given to them. 
Since plants will suffer for water when such soils have lost all 
but 2 to 3 per cent of their dry weight of the soil moisture, it 
follows that in 4 feet in depth of such a subsoil there is room for 
only 1.5 to 2 per cent of water, or 1 to 1.5 inches, to be applied 
at one time, without loss taking place by percolation below the 
depth of root action. It is plain, therefore, that on open soils 
the duty of water will be relatively small, unless great skill and 
rare judgment are exercised in its application. 

5. The frequency and thoroughness of cultivation after irriga- 
tion is another factor which will modify the duty of water. For 
the effectiveness of soil mulches is modified as well by the fre- 
quency of stirring as by its depth. The force of this statement 
will be better appreciated when the results given in the table 
which follows have been considered: 



724.1 


551.2 


545 


527.8 


6.394 


4.867 


4.812 


4.662 




23.88 


24.73 


27.1 


724.1 


609.2 


552.1 


515.4 


6.394 


5.38 


4.875 


4.552 




15.88 


23.76 


28.81 


724.1 


612 


531.5 


495 


6.394 


5.28 


4.694 


4.371 




15.49 


26.6 


31.64 



206 Irrigation and Drainage 

Table showing the loss of ivater from a virgin clay loam, through mulches 1, 2, 

and 3 inches deep, when cultivated once in two weeks, once per week, and 

twice per week 

Not Once in Once per Twice per 
cultivated 2 weeks week week 

Cultivated 1 inch deep— per acre pe.h acre per acre per acre 

The loss in tons per 100 days was 

The loss in inches per 100 days was. . 
The percentage of water saved was . . 

Cultivated 2 inches deep— 

The loss in tons per 100 days was 

The loss in inches per 100 days was.. 
The percentage of water saved was. . 

Cultivated 3 inches deep— 

The loss in tons per 100 days was 

The loss in inches per 100 days was. . 
The percentage of water saved was. . 

It will be seen from this table that with each of the three 
depths of cultivation the loss of water decreased with the fre- 
quency, so that the per cent of moisture saved by the cultivation, 
when computed on that which was lost with no cultivation, was 
more than 31 for 3 inches deep twice per week, as against a sav- 
ing of only 15 per cent where the same cultivation was made only 
once in two weeKS. That is to say, if one is cultivating ground 
of this character 3 inches deep twice per week, the saving over 
no cultivation may be at the rate of 2.29 tons per acre per day, 
or 22.9 tons per each 10 days, or 2 acre-inches per 100 days. 

The results presented in the table were obtained in our 
plant-house, with cylinders 52 inches deep and 18 inches in 
diameter, filled with soil under a nearly still air and a compara- 
tively low mean temperature, not exceeding 55° F., during the 
short days and long nights of December and January, so that 
the observed losses in the several cases must be looked upon as 
small, and below what may obtain under field conditions. It is 
plain, therefore, that in orchard irrigation and in arid climates, 
under a clear sky, dry air and high temperature, the duty of 
water during the long seasons may be very materially increased 
by adequate cultivation, and decreased by the lack of it. 

The same will also be true, but in a less marked degree, 



i 



Conditions Modifying Duty of Water 207 

with all cultivated crops where the soil is not completely shaded 
by the plants on the ground. 

6. TJie closeness of planting is another factor which affects 
the duty of water when this is expressed in terms of land served, 
rather than in terms of crop produced. This is particularly true 
in climates where a rainy season contributes a considerable por- 
tion of the moisture needed to produce a crop ; because if one is 
contented with a small yield per acre, a comparatively thin stand 
upon the ground, with thorough tillage, may often be brought to 
full maturity with a relatively small amount of water applied 
by irrigation, thus making the duty of water to appear very high, 
whereas if the plants were made to stand as closely as the sun- 
shine would permit, much more water, when expressed simply 
in acre-inches, would be required. The real duty, however, might 
be even higher in the second case, when expressed in terms of 
yield per acre. 

7. The fertility of the land is still another factor which 
affects the duty of water, tending to make it appear less the 
richer and more fertile the soil is, when the standard of com- 
parison is the unit area rather than the yield of crop. This 
apparent decrease in the duty results from the larger evaporation 
of water which takes place from the more vigorous growth of 
vegetation, and the closer stand which the larger amount of 
available plant-food renders possible. In such cases as these, 
however, the real duty of water is higher on the most fertile soil, 
when this is based upon the actual yields per acre ; not so much 
because the plant uses the water more economically, as that the 
necessary loss from the soil itself is relatively less with the large 
yield than it is with the small yield per acre. The loss from the 
soil direct may even be actually larger with the smaller crop on 
the ground, on account of a less complete shading and stronger 
air movement close to the surface. 

8. The frequency of applying water also modifies the quantity 
which will be used during a season. This may be true even 
when the greatest skill is exercised in the application of the water. 
In the first place, too frequent application of water in small 
quantities at a time not only increases in a marked degree the 



208 Irrigation and Drainage 

direct loss of moisture from the wet, unmulched soil ; but it may 
have a tendency, as has been pointed out, to induce a superficial 
development of roots, causing the crop to show signs of need of 
water sooner than would be the case if a smaller number of more 
thorough irrigations were resorted to. This is so, not only be- 
cause the water disappears sooner from the soil, but also because 
of the larger amount of root-pruning which results from culti- 
vation where the roots are developed near the surface of the 
ground. 

It is probable that a large supply of water in the soil during 
the early stages of growth of many plants tends to develop in 
them a possibility for using more water. In some, at least, of 
our experiments with corn, oats, potatoes and clover, where we 
have started with like amounts of water in the soil, and have 
watered one set of plants every seven days while the others 
were allowed to go without water until the soil was so far ex- 
hausted that the plants were plainly suffering for want of mois- 
ture, it was found that these plants not only did not use water as 
rapidly after they were given it as did those which had been 
watered every week, but they used the water they did have with 
relatively greater economy. Whether this was because the plants 
were smaller, and thus presented a smaller surface to the air and 
sun, or whether the size or number of breathing pores per unit 
area of foliage was actually less, cannot yet be stated ; but it 
appeared evident that for some reason the plants which had not 
been watered at first were later not able to use the larger amount 
of water which was given to them, as they might have done had 
they been more freely watered at first. 

THE AMOUNT OF WATER USED IN IRRIGATION 

It is very difficult, indeed, to get data bearing 
upon this important subject which may be regarded as 
in every way satisfactory and trustworthy. Nearly all 
statistics are necessarily so general in their character, 
the exact amount of land to which the water of a 



Amount of Water Used in Irrigation 209 

stated canal is actually applied is so uncertain, and 
the amount of water lost by seepage and evaporation 
from the canal and its distributaries before the land to 
which it is nominally applied is reached, is so variable 
and indeterminate that the best which can be said 
regarding most available data is that they should be 
looked upon as only rough approximations. Further 
than this, it must be constantly borne in mind, when 
dealing with the problem of how much water is re- 
quired for irrigation, with all the variations of weather, 
climate, crops, soils and degrees of skill in applying 
water which exist, that were sufficiently exact data at 
hand covering a wide range of conditions, it would 
still be impossible to combine them into averages not 
requiring wide marginal allowances to be made when 
specific application is desired. But, notwithstanding 
all this, general statements may be helpful if only 
they are rightly considered. 

Referring, first, to Italy,* where irrigation has long 
been systematically practiced, it is generally calculated 
that in Piedmont one cubic foot of water per second 
will serve satisfactorily 55 acres of land ; but on ac- 
count of loss by evaporation and seepage, this is 
reduced to 51.4 acres, this providing sufficient for 
4.63 inches of water every 10 days during the irri- 
gation season. 

Under the canal of Ivrea, where a large amount 
of rice is grown, which is given more water than ordi- 
nary crops, one second -foot serves but 42.75 acres, or 
at the rate of 5.668 inches every 10 days ; and under 

*Baird Smith, Italian Irrigation, Vol. I. 

N 



210 Irrigation and Drainage 

the Gattinara canal, water is provided which may be 
applied at the rate of 5.289 inches per 10 days. But 
u r the Busca canal, where the utmost economy is 
pr ced and every drop is saved, the duty of water 
is so much increased that one second -foot serves 106 
acres, making a depth of water equal to 2.245 inches 
every 10 days for the irrigation season. 

Bringing all cases cited by Smith into one table, 
and expressing the second -foot in inches of water per 
10 days, the following results are found : 

Amount of water used for irrigation in Italy 



No. of acres 
per sec. foot 


No. of inches of water 
per 10 days 


No 
per 


. of acres 
• sec. foot 


No. of inches of water 
per 10 days 


51.4 


4.63 




99.3 


2.397 


45 


5.289 




80.4 


2.96 


106 


2.245 




66.62 


3.572 


100.6 


2.366 




61.8 


3.851 


63 


3.778 




66.6 


3.574 


90.6 


2.627 




69.2 


3.44 


50.3 


4.732 




63.9 


2.837 J 


70 


3.4 




67.2 


3.542 * 


77 


3.091 




90.4 


2.633 


69 


3.449 









This gives a general average for ordinary crops of 
3.39 inches of water every 10 days and 33.9 inches 
per 100 days, were it used at such a rate for so long 
a period. 

In the rice irrigation of Italy, the amount of water 
provided is said to be at the rate of 5.568 inches, 
5.921, 3.412, 9.521, and 3.334 inches every 10 days 
in as many districts, or an average of 5.55 inches per 
10 days. 



Amount of Water Used in Irrigation 211 

In Spain, where the rainfall is less than in Italy, 
and where greater economy of water is practiced, 19 
important allotments* of water give an average ot 

2.353 inches every 10 days for various sections ot 
that country. 

In France, in the Department of the Upper 
Garonne, contracts were made calling for water at 
the rate of three -fourths of a liter per hectare per 
second, which makes a duty of about 93.25 acres per 
second foot, or water applied at the rate of 2.552 
inches every 10 days. In the department of Vau- 
cluse, the concession was at the rate of only 1.361 
inches per 10 days. 

In Egypt, Willcockst states that in winter water 
is applied at an average depth of 10 c. m., equal to 
3.937 inches, once in 40 days, which is a rate of 
.984 inches once in 10 days; but in summer the first 
watering is at the rate of 11.5 c. m., equal to 4.528 
inches, while subsequent waterings are at the rate of 
3.412 inches in depth. Cotton requires this amount 
once in 20 days, or at the rate of 1.706 inches per 10 
days. Rice is given water at the rate of 3.412 inches 
once every 10 days, and maize gets the same amount 
every 15 days, or at the rate of 2.276 inches in depth 
every 10 days. 

Wilsonl gives a table of general averages of the 
duty of water in different parts of the world, which 
we put in the form stated below: 



*Hall, Irrigation Development, p. 523. 
tWillcocks, Egyptain Irrigation, pp. 234, 235. 
jManual of Irrigation Engineering, See. Ed., p. 49. 



212 



Irrigation and Drainage 



Amount of water used in irrigation in different countries 
Name of country No. of acres per sec. -ft. No. of inches per 10 days 



Northern India . . 

Italy 

Colorado 

Utah 

Montana 

Wyoming 

Idaho 

New Mexico .... 
Southern Arizona . 
San Joaquin Valley 
Southern California 



60 to 150 

65 to 70 

80 to 120 

60 to 120 

80 to 100 

70 to 90 

60 to 80 

60 to 80 

100 to 150 

100 to 150 

150 to 300 



3.967 to 1.587 
3.661 to 3.4 
2.975 to 1.983 
3.967 to 1.983 
2.975 to 2.38 
3.4 to 2.644 
3.967 to 2.975 
3.967 to 2.975 
2.38 to 1.587 
2.38 to 1.587 
1.587 to .793 



E. Perels* tabulates the duty of water in Algeria 
as follows : 

Water required for irrigation in Algeria 



Crops 


No. of 
waterings 


/ Water used n 

Each During the 
application season 


Length of 
culture period 






INCHES IN 


INCHES IN 


MONTHS 






DEPTH 


DEPTH 




Alfalfa . . . 


10 


1.575 


15.75 


6 


Vegetables . 


. 36 


1.575 


56.7 


6 


Cotton . . . 


\ 






i 


Flax .... 


[ ^^ 


2.52 


25.2 


5 i 


Sesame . . . 


) 








Maize ... 


4 


1.575 


6.3 


2 


Winter grain 


3 


3.937 


11.87 


7 


Oranges . . . 


. 12 


1.575 


18.9 


6 


Tobacco . . . 


4 


1.575 


6.3 


3 


Grapes . . . 


4 


4.725 


18.9 


3 



^1 



From another general table giving the duty of 
water in different countries, by Flynn,t the results 
which follow are derived: 



*Landwirthschaftlieher Wasserbau, zweite Auflage, p. 502, 
t Irrigation Canals and Hydraulic Engineering, p. 293. 



Amount of Water Used in Irrigation 213 



Amount of water used in irrigation in different countries 



89 
-90 



Locality 
Eastern Jumna Canal . . 
Western Jumna Canal . 

Ganges Canal 

Canals of Upper India . . 
Canals of India — average 
Bari Doab Canals .... 
Madras Canals (rice) . . 

Tanjore (rice) 

Swat River Canal, 1888-89 
Swat River Canal, 1889-90 
Western Jumna Canal, 1888 
Western Jumna Canal, 1889 
Bari Doab Canal, 1888-89 
Bari Doab Canal, 1889-90 
Sirhind Canal, 1888-89 . 
Sirhind Canal, 1889-90 . 
Chenab Canal, 1888-89 . 
Chenab Canal, 1889-90 . 

Nira Canal 

Genii Canal 

Juear (rice) 

Henares Canal 

Canals of Valencia . . . 

Forez Canal 

Canals south of France . 
Sefi. Canals, Southern France 
Sefi, or Lower Nile Canals 
Sefi, or Lower Nile Canals 
Canals of Northern Peru . . 
Canals of Northern Chili . . 

Canals, Lombardy 

Canals, Piedmont 

Marcite 

Sefi Canals, Victoria .... 



Name of 


No. of acres 


No. of inches 


country 


per sec-foot 


per 10 days 


India 


306 


.778 


11 


240 


.989 


( ( 


232 


1.026 


n 


267 


.891 


11 


250 


.952 


it 


155 


1.536 


(I 


66 


3.606 


11 


40 


5.964 


li 


216 


1.345 


a 


177 


1.202 


( < 


143 


1.664 


<( 


179 


1.33 


11 


201 


1.184 


11 


227 


1.049 


(( 


180 


1.322 


<( 


180 


1.322 


(( 


154 


1.545 


( ( 


154 


1.545 


(< 


186 


1.28 


Spain 


240 


.992 


ii 


35 


6.8 


it 


157 


1.516 


(I 


242 


.984 


France 


140 


1.7 


(< 


70 


3.4 


<< 


60 


3.877 


Egypt 


350 


.68 


(< 


274 


.867 


Peru 


160 


1.488 


Chili 


190 


1.253 


Italy 


90 


2.644 


( ( 


60 


3.877 


(< 


1 to 18 


238 to 13.22 


Australia 200 


1.19 



214 Irrigation and Drainage 

Amount of water used in irrigation— continued 

Name of No. of acres No. of inches 
Locality country per sec. foot per 10 days 

Sweetwater, San Diego .... California 500 .476 

Pomona, San Bernardino ... " 500 .476 

Ontario *' 500 .476 

California " 80tol50 2.975tol.587 

Canals of Utah Territory . . . Utah 100 2.38 

Canals of Colorado Colorado 100 2.38 

Canals of Cache la Poudre . . . " 193 1.233 

Canals of Colorado " 55 4.328 

It is apparent, from the data which have been 
presented, that the amount of water actually used in 
irrigation in different countries and for different crops || 
is an extremely variable quantity; so much so, indeed, 
that it is hardly possible to deduce from available sta- 
tistics a mean value for the duty of water. But, using 
the 100 cases at hand from all parts of the world, and 
excluding those which apply to rice culture and the 
irrigation of water-meadows and sugar cane, it ap- 
pears that a cubic foot of water per second is made 
to serve on the average 117.6 acres. If this water 
were applied to the land once in 10 days, it would , 
cover the surface to a depth of 2.024 inches each ' 
watering, and during a season of 100 days would be 
the equivalent of 20.24 inches of rain. 

Sugar cane is a crop which demands large and fre- 
quent irrigations in order to secure the largest returns 
from the soil. In the Sandwich Islands one cubic 
foot of water per second is required for 41.6 acres of 
cane, and it is found that if the duty is made larger 
than 60 acres per second -foot, a falling off in yield is 



Highest Prohahle Duty of Water 



215 



sure to result. In India and Siam writers on this sub- 
ject state that from 43 to 45 acres is the usual duty 
of a second -foot. The mean value for good, thorough 
watering appears to be 43.2 acres per second -foot, or 
a depth of water aggregating, for the year, between 19 
and 20 feet on the level. 

If reference is again made to the table on page 
198, it will be seen that this duty of water is much 
smaller than was realized in the experiments cited. 
According to the results there given, one second -foot 
should be able to serve the number of acres stated in 
the table below: 



The highest probable duty of water for different crops expressed in acres per 
second-foot for different yields per acre 



Yield per 


Wheat 


Barley 


Oats 


Maize 


Potatoes 


Clover hay 


acre 


ACRES 


ACRES 


ACRES 


ACRES 


ACRES 


ACRES 


15 bushels 


529.2 


593.0 


1002 


1039 






20 " 


352.8 


395.3 


751.5 


779.2 






30 " 


264.6 


296.5 


501.0 


519.5 






40 '' 


176.4 


197.6 


375.7 


389.6 






50 '' 


141.1 


158.1 


300.6 


311.7 






60 " 


117.6 


131.7 


250.5 


259.7 


2493.7 




70 " 




112.9 


214.3 


222.6 


2137.4 




80 " 




98.8 


187.9 


194.8 


1870.2 




90 '' 






167.0 


173.2 


1662.4 




100 '* 







150.3 


155.8 


1496.2 




200 " 











748.1 




300 " 










498.7 




400 '' 










374.0 




1 tOQ 













322.7 


2 tons 










. . . 


161.3 


3 " 












107.6 


4 " 












80.7 



216 



Irrigation and Drainage 



In constructing this table, the season of growth 
has been taken at 100 days for wheat and oats, 80 
days for barley, 110 days for maize, 130 days for pota- 
toes, and 60 d-ays for one crop of clover hay. It has 
further been assumed that the ground at seeding time 
is well supplied with moisture, while at harvest it is 
only so much dried out as to have just become ready 
for another watering. 

As in the experiments which gave the fundamental 
data for the table above, the soil was more closely 
planted than is practicable under field conditions, the 
loss of water by evaporation from the soil of the field 
is likely to be greater, relatively, than was the case in 
the experiments ; hence, the observed duty of water is 
likely to be lower than the table indicates. Again, 
in the case of the smaller yields per acre, the evapo- 
ration from the soil will necessarily be relatively larger 
than w^here the heavier crops are produced ; hence, the 
duty expressed for water when the yields are small is 
likely to be farther from the possibilities than in the 
cases where the yields i)er acre are larger. 

If the amount of water which the last table indi- 
cates is required to produce a crop of the various 
kinds is expressed in cubic feet, the figures will 
stand : 



8,640,000 ou. ft. of water may produce 7,056 bushels of wheat 
8,640,000 *' *' '' " '' " 15,030 " " oats 



6,912,000 " '* 

9,5040,000 " '' 

11,232,0000 " *' 

5,184,000 " " 



7,906 " ' barley 
15,580 " " maize 
149,620 " " potatoes 
322.7 tons of hay, 



I 



Duty of Water in Bice Culture 217 

where the number of cubic feet is the product of one 
second -foot into the number of seconds in the season 
of growth, and the number of bushels is the product 
of the yield per acre into the number of acres irri- 
gated. 

THE DUTY OF WATER IN RICE CULTURE 

The aquatic nature of the rice plant makes the 
demands for water quite different from those of ordi- 
nary agricultural crops, and so different are these 
needs that the quantity of water required to bring a 
crop to maturity is determined by quite different 
factors. The duty of water, therefore, in rice culture 
could not consistently be considered in connection with 
that of ordinary crops. 

The normal habitat of this plant is low, swampy 
lands, where the surface is more or less continuously 
under water, and where such lands are available under 
-suitable conditions for rice culture, they are largely 
brought into requisition for this purpose ; but the 
seeding of the ground and the harvesting of the crop 
make it needful that the fields shall be drained \ at 
times and at others flooded. Under these conditions, 
there can be but little waste from seepage, and the 
chief demands for water are created by the loss from 
evaporation from the surface of the water, from the 
growing crop, and from the wet soil when the fields 
have been drained, together with the amounts which 
are required for reflooding the fields after they have 
been drained. Occasionally threatened attacks upon 



218 Irrigation and Drainage 

the crop by insect enemies make an extrr '""^q: O- 

drainage necessary, and this increases th' 
water. Further than this, in order that t- jp may 

be the best, the water must not remain lov*^ stagnant, 
and this requires either alternate flooding md drain- 
ing, or else a considerable steady surplus flow of water 
over the fields. 

In order to secure more economical methods of 
seeding and harvesting the rice fields, this crop is 
extensively grown on naturally dry lands, which may 
be readily checked off into flooding basins, to which 
the water may be admitted and withdrawn at pleasure. 
In these cases, there is added to the demands for 
water already mentioned the loss from seepage. This 
loss from seepage may be so large that rice irrigation 
cannot be economically practiced on uplands unless 
they are quite fine and close in texture, so that the 
rate of seepage will be small, or unless the normal 
level of the ground -water is within a few feet of the 
surface. Even here the subsoil must be pretty close, 
or the loss of water by under -drainage will be too 
large. 

The various available sources of data regarding the 
duty of water in rice irrigation place the amounts of 
water used as varying all the way from one second -foot 
for 25, 28, 30, 35, 40, 55 and 66 acres of rice, thus 
making an average of 38.6 acres per cubic foot of 
water per second, and this is equivalent to covering 
the surface with water about 6.2 inches deep every 10 
days. 



D' ty of Water on Water-meadows 219 



THE QTY of WATEK ON WATER-MEADOWS 

In this ^x-m of irrigation, immense volumes of water are 
used on th». land. In Italy, where the practice has attained 
the highest .->cage of perfection, where it may have had its 
origin, and x. m which been introduced into France, and even 
into England at the time of the Roman invasion, the duty of 
water appears to average only about 1.5 acres per cubic foot per 
second. On these meadows in Italy there is maintained a nearly 
continuous flow of water, night and day, from September 8 to 
March 28 of each year, this being the legal time allotted to 
Marcite, or winter-meadow irrigation. 

The lands are so laid out that the roots of the grass over the 
whole meadow are continuously submerged beneath a thin veil 
of relatively warm running water, this being turned off only long 
enough to cut the grass, which is done two or three times during 
the winter season, the green grass being used for the winter feed 
of dairy cows, which are largely kept in the irrigated portions of 
Italy. So large is the quantity of water used during a single 
season on these meadows that did none of it drain away they 
would become submerged to a depth of 300 feet. 

Carpenter, quoting Mangon, states that in southern France 
and in the Vosges, where the most careful measurements of the 
water applied to the meadows have been made, amounts are used 
in some eases sufficient to cover the surface 1,400 feet deep ; 
and that of this great volume, as much water as 160 feet on the 
I'^vel sinks into and percolates through the soil of the field during 
a winter season. But even in the summer irrigation, as much as 
374 feet of water on the level are applied between April and 
July, while of this amount no less than 88 feet percolates into 
the ground or is evaporated. 

The meadows upon which these large volumes of water are 
applied are usually permanent ones, and have had their surfaces 
ntted with the greatest care, so that the relatively warm water 
may be kept steadily flowing over the surface about the roots of 
the grass in a thin veil until it is ready to cut, when it is turned 
off only long enough to remove the crop. 



220 Irrigation and Drainage 

In Italy these heavy and continuous irrigations stimulate 
the grass to grow the year round, and in the vicinity of Milan, 
where the irrigation canals are led through and beneath the 
city, relieving it of all its sewage, this warm and highly ferti- 
lizing water so stimulates the growth of grass that seven heavy 
crops are taken from the ground each year, aggregating, accord- 
ing to Baird Smith, 45 to 50 tons per acre, and in exceptional 
cases one -half more than this. 

It will be readily understood that the application of water 
to these winter and summer water-meadows in such large vol- 
umes has quite a distinct purpose from that of supplying the 
needed moisture for the transpiration of the grasses. In short, 
the practice has been found to be a sure way of greatly pro- 
longing the growing season of each year, and a cheap means of 
permanently maintaining a high state of fertility of the soil. 



THE DUTY OP WATER IN CRANBERRY CULTURE 

In the irrigation of cranberries, as in the case of rice and 
water-meadows, the purpose of the treatment is quite distinct 
from that of ordinary irrigation. It is true that this crop 
demands a large amount of water, but its normal habitat is such 
that ordinarily it is abundantly supplied by natural sub -irri- 
gation. In this case, the water is demanded chiefly to protect 
the crop against the ravages of insects and injury from frost, 
and to prevent winter-killing. 

As the surface of the ground-water is seldom more than one 
to two feet below the surface of the bog, and as the peat and 
muck above the water are at all times nearly saturated, the 
amount of water required for cranberry irrigation is but little 
more than that necessary to submerge the vines, which will 
rarely be more than .8 to 1.5 acre-feet. But, except for the 
flooding for winter protection, the demands for water are so 
peremptory and the time so short which can be allowed for sup- 
plying it, that but a low duty is possible when this is measured 
by the rate at which the water must be delivered. 



Duty of Water in Cranberry Culture 221 

When it is protection against frost which is required, the 
marsh must be given as much as 4 to 6 inches of water on the 
level in nearly as many hours. To do this will require a stream 
of 1 to 1.3 cubic feet per second per acre. But when the flood- 
ing is to destroy insects, the haste need not be so great ; while 
for winter flooding, a relatively small stream will answer the 
needs, as six weeks, if need be, may be taken in the flooding, 
and as the ground-water surface around the marsh is usually 
above the marsh itself, the loss from seepage is small, as must 
also be that by evaporation during the winter. 



CHAPTER VI 

FREQUENCY, AMOUNT AND MEASUREMENT OF WATER 
FOR SINGLE IRRIGATIONS 

To have become able to apply water to crops at 
the right time, in the i-ight amounts and in the best 
manner is to have attained the acme of the art of 
irrigation. Unfortunately, it is no more possible to 
bear a man to this position on the vehicle of language f J 
than it is a cook to the art of making the best bread. 
Both arts are founded upon the most rigid of laws, 
which may be readily and certainly followed when the 
conditions have been learned. But the minutias of 
essential details are so extreme that words fail utterly 
to convey them to the mind, and they must be per- 
ceived through the senses, to be grasped with such 
clearness as to lead unerringly to the right results. 
There are, however, general principles underlying the 
art, which may be readily stated, and, when com- 
prehended, place one in position to more quickly grasp 
the details essential to complete success in the appli- 
cation of water to crops. 

THE AMOUNT OF WATER FOR SINGLE IRRIGATIONS 

In humid climates, there is always more or less 
soil -leaching, resulting from super- saturation of the 

(222) 



Amount of Water for Single Irrigations 223 

soil during times of heavy or protracted rains. This 
leaching is usually looked upon as a necessary evil, 
which results in a waste of fertility. Whether this 
conviction is well founded, or whether a certain 
amount of soil washing is indispensable to unim- 
paired fertility, it appears to the writer is one of 
the important soil problems awaiting positive demon- 
stration. The accumulation of alkalies in the soils 
of arid climates, where relatively small leaching is 
associated with large evaporation, and the tendency 
of alkalies to become intensified where irrigation has 
been long practiced, are facts which suggest that 
there may be such a thing as too great economy of 
water in irrigation. 

But, waiving this possibilit}^ of demand for water, 
and all of those cases where the water is applied ^for 
other purposes than meeting the ordinary needs of 
vegetation, the fundamental conditions which deter- 
mine the amount of water which should be applied at 
a single irrigation are : (1) the capacity of the soil 
and subsoil to store capillary water; (2) the depth 
of the soil stratum penetrated by the roots of the 
particular crop ; (3) the rate at which the soil below 
the root zone may supply water by upward capillarity 
to the roots ; and (4) the extent to which the soil 
and subsoil have become dried out. 

On the other hand, the conditions which determine 
the frequency of irrigation are : (1) the amount of 
available moisture which may be stored in the soil ; 
(2) the rate at which this moisture is lost through 
the crop and through the soil; and (3) the degree 



224 Irrigation and Drainage 

of desiccation of the soil which the particular crop 
will tolerate before serious interference to growth le- 
sults. 

THE CAPACITY OF SOILS TO STORE WATER 
UNDER FIELD CONDITIONS 

Tke amount of water which may be stored in soils under 
field conditions varies between wide limits with the character 
and texture of the soils, and also with the distance of standing 
water in the ground below the surface. 

"When a fine sand will hold in the first foot above the 
ground-water 23.86 per cent of its dry weight of water, at 4 feet 
above it was found to hold only 8.12 per cent, and 8 feet above 
only 3.14 per cent of the dry weight. When these amounts are 
expressed in pounds per cubic foot, they stand only a little more 
than 23.86 pounds, 8.12 pounds, and 3.14 pounds, a cubic foot 
of the dry sand weighing about 105 pounds. 

In the case of a natural field soil of sandy clay loam with 
clay subsoil changing to a sand at 4 feet, and where the 
ground-water changed during the season from 7.6 feet below 
the surface to 8.4 feet, the water content of the soil was found 
to be as follows: 

1st ft. 2d ft. 3d ft. 4th ft. 5th ft. 6th ft. 7th ft. 

lbs. lbs. lbs. lbs. lbs. lbs. lbs. 

water water water water water water water 

July 25 10.44 16.91 14.81 10-38 7.82 13.66 22.29 

October 2 9.49 16.27 14.41 6 99 7.74 7.85 19-35 



Loss .95 .64 .4 3.39 .08 5.81 2.94 

During this interval there had been a rainfall of 10.84 
pounds per square foot. There is no doubt that in the upper 
4 feet a considerable part of the water was lost through surface 
evaporation. It is quite likely, also, that a portion of the loss 
shown in the 5th, 6th, and 7th feet was due to an upward capil- 
lary movement. But there is little reason to doubt that the 



Amount of Water for Single Irrigations 225 

chief loss shown in the lower three feet is due to downward 
drainage or percolation, owing to a lowering of the ground- 
water surface. 

The 8-foot column of fine sand, referred to above, lost water 
by percolation in 22 hours and 46 minutes, after full saturation, 
equal to 6.35 per cent of the dry weight of the whole column ; 
and as this must have come almost wholly from the upper 4 
feet, the water there must have been reduced in that time more 
than 12 per cent, which would leave a saturation of only 8 
per cent. 

But as plants would suffer severely for water in a soil of 
this texture when the moisture was brought down to 4 per cent, 
it is plain that only from 2 to 4 per cent of the weight of such 
a soil can be added at one irrigation without entailing severe 
loss by percolation below the depth of root-feeding. Taking a 
cubic foot of such a soil at 105 pounds, the maximum irrigation 
which could be applied without severe loss, supposing the ground 
to be wet down 5 feet and the soil to have dried 3 per cent, 
would be 15.75 pounds per square foot, or 2.86 inches in depth. 
The sand in question, however, is more open than most agri- 
cultural soils; hence it follows that more than 2 inches of water 
may be safely applied at one irrigation to any crop much in 
need of water. 

By taking samples of soil in a field of maize and clover 
when the corn leaves were badly curled and when clover wilted 
quite early in the forenoon, the following moisture conditions 
were found: 

Soil moisture relations when growth is brought to a standstill 
Depth of sample Clover 

PER CENT 

0-6 ju. clay loam 8.39 



6-12 
12-18 
18-24 
24-30 
40-43 



" 8.48 

reddish clay 12.42 

" 13.27 

sandy clay 13.52 

sand 9.53 



Maize 


Fallow ground 


PER CENT 


PER CENT 


6 97 


16.28 


7.8 


17.74 


11.6 


19.88 


11.98 


19.84 


10.84 


18.56 


4.17 


15.9 



226 Irrigation and Drainage 

The moisture contained in the fallow ground, determined at 
the same time, shows how much water such a soil may hold 
against a drought and against percolation below root action. 

The amount of moisture, too, in this fallow ground happens 
to stand just at the under limit for most vigorous plant-growth 
in this type of soil, while the upper limit is given in the table 
below for comparison : 

Showing upper and lovjer limits of best amount of soil moisture for one type of soil 

Kind and depth Lower limit of Upper limit of Available 

of soil soil moisture soil moisture soil moisture 

PEU CENT PER CENT LBS- FEB CU. FT. 

Clay loam, first foot 17.01 25 77 6.92 

Keddish clay, second foot 19.86 24.3 4.112 

Sandy clay, third foot 18.56 24.03 5.722 

Sand, fourth foot 15.9 22.29 6.786 

Total 23 55 

It will be seen from this table that to bring the surface four 
feet of soil from the lower limit of the best productive stage of 
water content to the upper limit requires an application of 23.55 
pounds per square foot, or a depth of irrigation equal to 4.527 | 
inches. 

It is quite certain that with a greater distance to standing 
water in the ground, the 4th foot, and probably also the 3d foot, 
could not have retained the amount of water shown by the table ; ■ 
and, hence, that an irrigation of 4.5 inches on such a soil would f 
have resulted in some loss by percolation below the depth of 
root feeding. 

If it should happen that a soil like the one in question be- 
came as dry as is shown in the table on page 225, then the depth 
of irrigation required to bring the moisture content up to the 
upper limit of productiveness would be for the maize 11.37 inches, 
and for the clover 9.39 inches, supposing the ground- water to be 
at the time not more than 7 feet below the surface. 

It follows, therefore, from the observations and data pre- 
sented, that the amount of water required for one irrigation, 
where the soil has not been permitted to become too dry, and 



Depth of Boot Penetration 227 

where the aim is to bring the soil moisture to the upper limit 
of productiveness without causing percolation below 4 or 5 feet, 
will range from about 2.5 inches on the most open soils to 4.5 
inches on soils of average texture. But when excessive drying 
of the soil has taken place, then the amount of water applied 
may range from 3.75 inches on the most open soils to as high as 
even 11 inches on that which is of medium or fine texture. It 
should be understood that many soils, when they become very 
dry, develop shrinkage cracks, which permit very rapid and ab- 
normally large percolation if excessive amounts of water are 
applied at one time, and this without saturating the soil, the 
water simply di'aining through the large open channels. In such 
eases repeated smaller applications of water will ensure less loss 
by percolation, permitting the soil to expand and close up the 
shrinkage cracks. 



THE DEPTH OP ROOT PENETRATION 

The greater the depth to which the roots of a 
crop iivdy feed to advantage in the soil, the larger 
may be the amount of water applied to the field at a 
single irrigation without any passing beyond the zone 
of root action, simply because 2 feet of soil will store 
more water than 1 foot, and 10 feet more than 5. But, 
further than this, where the roots of a plant penetrate 
the soil deeply and spread widely, a much smaller per 
cent of water in the soil will enable the plant to ob- 
tain enough to carry on its functions to good advan- 
tage. This is so because the roots go to the moisture, 
and do not, therefore, need to wait for the moisture to 
come to Them at the extremely slow rate it is known 
to travel in a relatively dry soil. Then, too, when a crop, 
by reason of its great spread of root, is able to meet 



228 



Irrigation and Drainage 




Fig. 37. Penetration of roots of prune on peach in arid soil of 
California. (Hilgard.) 



Depth of Hoot Penetration 



229 



its needs in a dryer soil, it is evident that a much 
higher duty of water is possible, for the simple reason 
that none can be lost by percolation, and much less 
will be lost by surface evaporation, even with deficient 
tillage. 

We have already called attention to the probable 
deeper rooting of plants in soils of arid regions, where 




Fig. 38. Penetration of apple root in Wisconsin, 7 years planted. 
Depth 9 feet. (Goff.) 



there is less distinction between the soil and subsoil, 
than in those of humid climates. Since writing that 
section, we have received Professors Hilgard and 
Loughridge's Bulletin 121, in which they emphasize 
this point by placing in evidence a photo -engraving 
of a prune tree on a peach root exposed in the soil 
to a depth of 8 feet, and represented in Fig. 37. The 
method they have used in exposing the root appears, 



230 



Irrigation and. Drainage 



from the photograph, to have destroyed nearly all but 
the main trunks, unless it was true that the active 




][%%: '>'^^, 




Fig. 39. Penetration of grape roots in Wisconsin soil. 
Depth 6 feet. (Gofe.) 

absorbing surfaces were chiefly still more deeply buried 
in the soil than the excavation extended. This appears 
quite likely to have been the case, for this penetra- 



Depth of Root Penetration 



231 



tion is no greater than has been found in soils in 
Wisconsin. 




Fig. 40. Penetration of raspberry roots in Wisconsin soil. 
Depth 5 feet. (Goff.) 

Professor Goff has washed out the roots of the 
apple, grape, raspberry and strawberry, showing" the 
extent of their development in a loamy clay soil 



232 



lynigation and Drainage 



underlaid bj^ a reddish clay subsoil, which changed 
through a sandy clay into a mixed sand and gravel, 
at 4 or more feet. His photographs, reproduced in 
Figs. 38, 39, 40 and 41, show to what extent the roots 
of these fruits penetrate the soils and subsoils of 




Fig. 41. Penetration of roots of strawberry in matted rows in Wisconsin 
soil. Depth 22 inches. (Goff.) 

Wisconsin, where the annual rainfall ranges from 28 
to 40 inches. It will be seen from the legends that 
the roots of the apple have extended to a depth of 
fully 9 feet, the grape more than 6, and the raspberry 
more than 5. It is plain, therefore, that even in the 
soils of humid climates the roots penetrate so deeply 
that the moisture of the surface 8 to 10 or 12 feet is 



Depth of Root Penetration 



238 



laid under tribute by them, and 
this makes it clear that the stor- 
age room for water in the soil for 
many of the fruits may be much 
greater than we have pointed out 
above. 

In the case of the strawberry, 
however, the figure shows that it 
is a particularly shallow feeder, 
and, therefore, is certain to suffer 
severely in dry times if not irri- 
gated. 

In Fig. 42 are shown the roots 
of alfalfa only 174 days from 
seeding. These had forged their 
way through so close a clay subsoil 
that more than four days of con- 
tinuous washing were required to 
dissolve away a cylinder of soil 1 
foot in diameter and 4 feet long. 
The roots, however, had penetrated 
this soil to a depth exceeding four 
feet, and the nitrogen-fixing tuber- 
cles were already developed 22 
inches below the surface. 

In the rigid data here pre- 
sented, combined with that shown 
in Figs. 10 and 11, we have a 
rational basis upon which to build 
a practice of irrigation, so far as 
that relates t(? the depth of soil 



Fig. 42. Roots 
in Wisconsin 
from seeding. 



of alfalfa 
174 days 



234 Irrigation and Drainage 

which may be moistened and yet be within the reach 
of plants. 

THE FREQUENCY OF IRRIGATION 

The data presented in the last two sections are a 
portion of those required to understand the rationale 
of this important subject. Viewed from the standpoint 
of labor involved in distributing water for irrigation, 
it is evident that the fewer the number of irrigations 
the smaller may be the labor involved and the lower 
the cost. Moreover, the less often the surface of the 
soil is wet, the smaller will be the loss of water by 
evaporation and by seepage in bringing the water 
to the fields ; hence, the higher will be the duty of 
water. 

The most general rule which can be laid down 
governing the frequency of irrigations and the amount 
of water to be applied at one time, is to apply as much 
water to the soil which is available to the crop as the 
crop will tolerate without suffering in yield or quality, 
and then husband this water with the most thorough 
tillage practicable, in order to reduce the number of 
irrigations to the minimum. 

It has been shown that a crop of maize yielding 
70 bushels per acre may be brought to maturity in 110 
days with 11.75 acre-inches of water. It has also been 
shown that a soil of medium texture may cany in the 
surface 4 feet 4.5 inches of available water, or, if ex- 
tremely open, 2.5 inches. Could so high a dutj^ of 
water as this be attained under field conditions, three 



Frequency of Irrigation 235 

irrigations would be required for such a crop of maize 
on the medium soil and five on the most open one, 
making the intervals between waterings 37 and 22 days; 
but if the yield was 100 bushels per acre instead of 
70, the number of irrigations required would be four 
or seven, and the intervals between waterings would be 
27 days for the medium soil and 15 days for the most 
open one. 

Computing for wheat on a similar basis, with a 
yield of 40 bushels per acre, requiring 12 acre -inches 
of water under the conditions of the highest duty, the 
number of irrigations would have to be three or five, 
at intervals of 33 or 20 days, according as the texture 
of the soil was medium or very coarse; while a crop 
of barley yielding 60 bushels per acre in a period of 
88 days would need 12.84 acre -inches, to be applied in 
three or five irrigations, at intervals of 29 or 18 days. 

These three cases may be taken as types of the 
highest limits likely to be attained under the best of 
field conditions, and they may serve as standards 
toward which we may strive with the satisfaction of 
knowing that extremely good and thorough work has 
been done if they are attained. 

It will be desirable, now, to review the literature of 
the frequency of irrigation, and see how actual practice 
in various parts of the world corresponds with the 
conclusions stated. 

In southern Europe, wheat is irrigated three to four 
times; in India, five times during the hot seasons and 
four times for the crop of the cool season. In the 
United States, Colorado irrigates two, three and, occa- 



236 Irrigation and Drainage 

sionally, four times, two being the usual number ; in 
-New Mexico, the ground is irrigated once before and 
once after seeding and five times later, making seven 
times in all ; while in Utah the number of w^aterings is 
three to five. 

The average number of irrigations appears to be 
from three to five for wheat in all parts of the world. 
But it should be understood that these irrigations are, 
in all cases, supplemented more or less with natural 
rainfall. In Colorado, for example, where the usual 
number of irrigations is two, the rainfall from April 1 
to July 1 is often as great as 8 inches, or two- thirds 
the amount of water required for a yield of 40 bushels 
per acre, thus making the number of irrigations amount 
practically to six rather than two, and the mean interval 
16% days, instead of 33 to 20. 

It must be remembered, further, that while the 
irrigations of wheat are in all cases supplemented with 
natural rainfall, the yield per acre does not average 40 
bushels ; hence the agreement of the theoretical fre- 
quency of irrigation, 33 to 20 days, with that actually 
practiced is more apparent than real. 

In Egypt, maize is irrigated every 15 daj'S, which 
would make seven waterings for the crop. Barker states 
that six irrigations are given to a crop in the Mesilla 
valley, New Mexico; while in Italy three is the usual 
number. But here, again, the spring and early summer 
rainfall is quite large; so large, indeed, that much maize 
is grown without irrigation. It appears, therefore, that 
where this cro'p must really depend upon irrigation 
for the water needed, it must be applied as often as 



Frequency of Irrigation 237 

every 15 to 20 days, and our experimental studies place 
it at 15 to 27 days for yields of 100 bushels per acre. 

The intervals between the irrigations for other 
cereals will be found to fall between those for wheat 
and maize, oats requiring the largest amount of water 
and barley the least, to mature a large crop. 

In the irrigation of clover and alfalfa, the usual 
practice is to irrigate once for each crop. But there is 
little question that larger yields for each crop may be 
secured where the number of irrigations is doubled^ 
giving six where the number of crops is three, and teu 
where it is five, thus making the length of the interval 
10 or 20 days. 

With other meadows, the general custom is to give 
these as much and as many waterings as the water 
supply will permit. In Italy, the summer meadows are 
watered every 14 days. In southern France they are 
watered every 5 to 18 days, and on the average every 
10 days. Winter water meadows, as has been stated, 
are watered with a nearly continuous flow of water over 
their surfaces. 

With potatoes, the custom is usually to depend upon 
the natural rainfall to bring the crop nearly or quite 
to blossoming, and then to irrigate twice on nearly 
level fields, and three to four times where the slopes are 
steep or where the soil is very porous and coarse in 
texture, thus making an interval for this crop of 20 
to 40 days. 

For this crop our experimental studies indicate that 
8.24 acre-inches may produce 400 bushels per acre ; 
hence, that two to four irrigations might be sufficient 



238 Irrigation and Drainage 

for a full season, starting with the ground in good con- 
dition as regards moisture at time of planting, making 
the possible interval 33 to 65 days. 

Fruit trees in Sicily and southern Italy are watered 
12 to 25 times during one season or once every 7 to 14 
daj'S. The peach and apple in Mesilla, New Mexico, are 
watered once at the beginning of winter, once early in 
Januarj^ and four or five times between April 1 and 
September 30, thus making the interval for the growing 
season 30 to 40 days. In Algeria and Spain, oranges 
are irrigated the year round — every 15 days in spring 
and summer, but at longer intervals the balance of the 
year ; and it is only on the heavy soils that irrigation 
is dispensed with during the rainy season. Grapes, 
when irrigated, are usually watered every 10 to 20 
da3'S, and young vineyards oftener than those more 
mature. 

Rice in Italy is kept flooded from the time of 
seeding until the plants are coming into bloom, and 
then the water is drawn off, but the fields are irrigated 
afterwards every few days. In Egypt the water in 
the rice basins is changed every 15 days, and in India 
a crop of rice gets as many as twelve waterings. 

In South Carolina, Mr. Hazzard informs me that 
their custom is to clay the seed to prevent it from 
floating, and then to flood the fields, keeping them so 
until the rice is well up, when the water is drawn off 
for 3 days to allow the plants to become rooted in 
the soil, when the fields are again flooded for 3 weeks, 
but changing the water everj^ 7 daj^s. The water 
is again drawn off for 30 days, to give the fields two 



Measitrement of ^yater 239 

dry lioeings, when flooding is again resorted to and 
maintained until the crop is matured. 

THE MEASUREMENT OF WATER 

The man who has become expert in handling water 
for irrigation really needs no means for measuring 
the amount required for the watering. His judg- 
ment, based upon an examination of the soil, is more 
reliable as to when enough has been applied than any 
measurement which could be made. But as soon as 
the same source of water becomes the joint property 
of a community, or wherever water is sold to consumers, 
means for measurement and division become indis- 
pensable. For the user of water, too, a definite knowl- 
edge of the exact amount he is putting upon a given 
area of land is very important, until he comes to know 
the needs of his land and of his crops for water ; be- 
cause without this knowledge he is liable to run on 
for years, using too much or too little water, leading the 
water too slowlj^ or too rapidly through the furrows, 
causing waste by deep percolation or too shallow wet- 
ting of the soil. If he knows that he has put the 
equivalent of 3 inches of water upon his field and only a 
quarter of the surface has been wet, it is certain that 
his method has been faulty and a large part of the 
water used has been lost. 

UNITS 'OF MEASUREMENT 

From the standpoint of the agriculturist, there is 
no unit for the measurement of water used in irrigation 



\ - 



240 Irrigation and Drainage 

so satisfactory as one which expresses the depth of 
water to be applied to a uuit area, and the acre -inch 
for English-speaking people, or the hectare -centimeter 
for those who nse the metric system, should become 
universal. Rainfall is now universally measured in 
units of depth, and, as irrigation is intended to make 
good deficiencies of rainfall, it would simplify matters 
greatly if the irrigator could call for the depth of water 
he desired. 

An acre-inch is enough water to cover 1 acre 1 inch 
deep; and 10 acre -inches of water is enough to cover 1 
acre 10 inches deep, or 10 acres 1 inch deep. As an 
acre contains 43,560 square feet, 12 acre-inches is equal 
to 43,560 cubic feet of water, and 1 acre -inch equals 
one -twelfth of this amount, or 3,630 cubic feet. As 
there are 1,728 cubic inches in a cubic foot, and 231 
cubic inches in a gallon, 1 cubic foot equals 7.48+ 
gallons, and 1 acre -inch equals 27,150 gallons. 

As 1 cubic foot of water at 60° F. weighs 62.367 
pounds, 1 acre -inch equals 226,392 pounds, or 113.2 
tons of 2,000 pounds. 

Another measure frequently used in the gauging of 
streams, and also used as an irrigation unit, is the 
second-foot, which means a discharge or flow of water 
equal in volume to 1 cubic foot per second of time; 
and a stream having the volume of 1 second -foot would 
supply an acre-inch in 3,630 seconds, or in 30 seconds 
more than one hour. In 24 hours, a stream of 1 
second-foot would supply 23.8 acre -inches, and would 
cover 7.93 acres of land with water 3 inches deep. 

Still another unit in common use in the western 



Measurement of Water 241 

United States is the miner's inch, which is the amount 
of water which may flow through an opening 1 
square inch in section in one second under a certain 
pressure or head. But the legal pressure varies in 
different states ; hence, the miner's inch has not a 
fixed and definite value. In California 50 miner's 
inches are usually counted equivalent to 1 second -foot, 
while in Colorado only 38.4 statute inches are required 
for a second -foot. 

Where a larger unit of measure is desired than 
either of those named, the acre -foot is sometimes 
used. This is an amount of water required to cover 
an acre 1 foot deep, and is, therefore, equal to 12 
acre -inches. 

METHODS OF MEASUREMENT OF WATER 

m Much and long as irrigation has been practiced, and impor- 
' tant as the subject is, especially in communities where water 
is scarce and where each user has need of every drop of water 
he can get, there appears even yet to have been devised few 
methods of measuring or of apportioning water among the users 
which possess the degree of precision which could be desired. 

In the ease of individual irrigators, where the water is 
pumped and stored in reservoirs, to be used as desired, the area 
of the reservoir and the amount the water is lowered in it fur- 
nish the needed data for determining the amount which has 
been applied to a given area of land. Or, in the case of direct 
application of the water pumped to the land, the rate of the 
pump may be known, and thus, through a knowledge of the time 
of pumping, furnish an approximate measure of the water used. 
In the great majority of cases, however, a knowledge of the 
amount of water used in irrigation must be gained in some other 
way. 



I 



242 



Irrigation and Drainage 



The Method of Time Division 

Where the amount of water carried in a ditch, lateral or 
pipe is not so large but that an individual may use the whole 
of it to advantage, the usual and the simplest method of divid- 
ing the water is on the basis of time, allowing each user to 
have the whole stream a specified number of hours and minutes, 
making the length of the time proportional to the amount of 
water to which each user is entitled. 

With this method, it is customary to issue to the various 
users under the ditch, at the beginning of the irrigation season, 
printed schedules or tickets, covering the whole or a portion of 
the season, which specify the dates upon which they will be 
entitled to the use of water, and the length of time they can 
have it, as illustrated by the following ticket: 



j^«_rCi.rfi_»^ 



•S WATHK TICKET NO-vfJT. 

I DISTRICT N0.<^-..- -DITCH NoC^ 

I Spnngville.UtQl). CM^^U^ J^2, 1896 

Youav* antltud to th« us* et th« uiatcp on 
ttao SiHf. .,Amy of_^^lf;^2<«C:-ijf. ,.^_ m\ ^.'^^.^ra. , until V -"^td. of th« 



^Ji 



Vou aive then v«qulvod todlsoontlnuo Ita us« and tupn it off youp l»nd< 

WAliTEl^ BIRD, watavmastor. 

j;t 7^ v^ jjr z{i Tjr -jjr ^;s Tji Tjr Tjr z»s ■z;*, ^{1 •jy »»i ^^s -zjr 2J1 Tjr ^;i Tjr T^i i}ri5r-i;iT^- 





With this system, if one man is entitled to two, three or 
four times the amount of water that a neighbor is entitled to, 
the length of his period is two, three or four times as long: 
and, as shown by the ticket, a regular rotation is followed, the 
water returning to the same user after the same number of 
days. 

Where the water must be used day and night, as should be 
the case where water is scarce and is allowed to run continuously 
to reduce waste, in order to prevent the night use of water fall- 
ing always upon the same individuals, the rotation period may 



Measurement of Water 



243 



be made to include a fraction of a day, say 8% days instead of 
8, as in the one cited ; or, after a certain number of rotations, 
the water may be given first to a different member in the 
circuit, and thus change the time of day at which each gets 
his turn. 

In those eases where the supply of water in the ditch is 
always the same, this is the most accurate and best method of 
dividing water which has been devised, and where the amount 
of water which the ditch carries is known, it gives every one a 
definite knowledge of the amount of water he is using. 

It often happens, however, that the volume of water changes 
from time to time, and when this is true those who chance to 
be using water when the supply is high will receive most. 
But if the period of rotation is short, the injustice will seldom 
be very great, and where the periods of rotation are short, the 
service is usually more convenient and better for other reasons 
than that of a more equitable division of the water, because it 
permits a user to apply his water to certain fields one date and 
to another on his next turn, thus permitting him to do his fit- 
ting and cultivation between irrigations to a greater advantage. 



^ 



[>^ 



-^^ 




The Subdivision of Laterals 

Where the lateral carries too much water to be used to 
advantage by single indi- 
viduals, this may be sub- 
divided readily into two 
exactly equal portions, and 
these two divisions may 
be again subdivided into 
two precisely equal streams. 
But in order that the di- 
vision may be exact, it 
must be done in certain 

ways, as represented in Fig. 43. If the two branches of the lateral 
form equal angles with the main, have the same fall, and their 
bottoms at the same level where they start, they will carry equal 



B 



\7 



M 



Fig. 43. Branching of canal to divide -water 
equally (A and £) and unequally (C), 



244 Irrigation and Drainage 

volumes of water if their dimensions are exactly the same as 
shown at A and B. But if the division is made as at C, or in 
any other manner, which makes the two arms in any way 
unlike, one will carry more water than the other. So, too, if 
care is not taken to keep the main and the two branches clean 
where the division is made, it will not be exact. 

When an effort is made to divide the main into. two unequal 
parts, or into an odd number of equal parts, the task becomes 
an extremely difficult one, and one which is not likely to be 
accomplished, and the attempt should be avoided. 

The cause of the difficulty is found in the fact that the water 
travels with the greatest velocity in the center of the stream 
and diminishes in speed as the sides are approached, so that if 
the main is divided into two branches which have cross -sections 
in the ratio of 1 to 2, the larger arm will carry more than twice 
the amount of the smaller one, because it must take a larger 
share of the water moving in the central portion of the main. 
Or if the main is divided into three equal laterals, then the 
central branch is sure to carry more water than either of the 
two taking the water from nearer the sides, and it is not prac- 
ticable to so adjust the dimensions of these branches that with 
varying volumes of water moving in the main the desired ratios 
shall always be secured in the divisions. 

The Use of Divisors 

When it is desired to remove from a ditch a certain portion 
of the amount of water which it is carrying, this is sometimes 
attempted by means of an arrangement represented in Fig. 44, 
called a divisor, in which the portion A is set into the channel 
some fractional part of the whole width, determined by the 
amount which it is desired to take out. Thus, if it was desired 
to take out one -fifth of the stream, and the lateral had a width 
of 40 inches, the divisor would be set in toward the center 8 
inches. But from what has already been said, it follows that 
less than one-fifth of the water can thus be removed, for the 
two reasons, that the section of the stream removed does not 



^^ 



Fig. 44. One form of water divisor. 



Division of Water 245 

have the mean velocity of the part remaining, and, having to 
change its direction to one at right angles, its velocity is still 
further checked in making the turn. The smallest users of water 

by this system, therefore, in- . 

variably receive an amount >^ 

which is less than they are 
entitled to use, while the larger 
users receive more. In order 
to reduce this inequality of 
division, the practice of insert- 
ing a weir-board in the canal 
just above the divisor, so as to 
restore a more nearly equal velocity across the stream, is some- 
times adopted; and if the canal is broadened above the measur- 
ing-box, so that the water a,pproaches the weir slowly and passes 
over it smoothly without contraction, Carpenter states that the 
method will give as satisfactory results as any with which he 
is acquainted. 

The Use of Modules 

A module is defined as a means of taking out of a canal a 
definitely specified quantity of water, measured as so many inches, 
cubic feet per secoad, or other units, rather than the simple 
division of a stream into a certain number of parts, as is the 
case where the divisor is used. 

Two types of modules are employed, one based upon the 
principle of the weir as a means for measuTing water, and the 
other on the laws governing the flow of water through orifices. 
If it were readily practicable to establish and maintain any 
desired pressure at a weir or an opening, water could be appor- 
tioned for irrigation with satisfactory precision with the aid of 
modules, but no method for doing this has yet been devised, 
although much study through many centuries has been devoted 
to it. 

The spill-box, 'invented by A. D. Foote, and represented in 
Fig. 45, is, perhaps, as satisfactory a means for maintaining a 



246 



Irrigation and Drainage 



nearly uniform head against either a weir or an opening as has 
yet been devised. Its essential feature is a long, sharp lip, 
over which the water may spill back into the canal in a thin 
sheet, and thus maintain a nearly constant pressure back of 




Fig. 45. Spill-baek method of dividing water. 

the lip of a weir or above an opening. But this arrangement 
does not and cannot maintain a constant pressure where there 
is any considerable fluctuation in the volume of water in the 
main canal; and, since the depth of water above the opening 
or lip of the weir must always be small, even a slight change 



Division of Water 247 

in the depth of the water over the lip of the spill -back must 
make a perceptible difference in the discharge. 

Further than this, where the form of the opening is designed 
to be made longer or shorter by means of a sliding valve accord- 
ing as more or less water is desired, the amount discharged, 
even when the head is maintained rigidly constant, is not 
directly proportional to the length of the opening, because the 
number of inches of margin upon which the resistance to flow 
depends does not maintain a constant ratio to the cross -section 
of the opening. The more margin there is in proportion to the 
area of the opening, the greater must be the loss of discharge 
through friction and contraction, so that the most exact and 
generally satisfactory way of apportioning water among users 
which has yet been devised, is that of bisecting the stream until 
its volume has become suitable for individual use, and then sub- 
dividing by time under some system of rotation. 



CHAPTER VII 

THE CHARACTER OF WATER FOR IRRIGATION 

The characteristics which determine the suitability 
of water for the purposes of irrigation must depend 
upon the chief objects for which the water is used : 
whether it is to control temperature, as in the case of 
winter -meadows and in cranberry culture ; to supply 
plant -food, as in the case of summer water-meadows ; 
to meet the simple need of water for the transpiration 
of the growing crop, or to deposit sediments for the 
purpose of building up the surface of low-lying areas, 
as in the case of warping. 

TEMPERATURE OF WATER FOR IRRIGATION 

Where one of the prime objects in the use of water 
for irrigation is to stimulate plant -growth, the warmer 
the water is within the natural ranges of temperature 
the better are the results. According to Ebermayer, 
when the temperature of the soil in which a crop is 
growing has been lowered to from 45° to 48° F., phys- 
iological processes are brought nearly to a standstill 
in it, and the maximum rate of growth does not be- 
come possible until after the soil temperature has 
risen above 68° to 70°. It is plain, therefore, that if 
large volumes of cold water were applied to the soil at 

(248) 



Temperature of Water for Irrigation 249 

one time, and especially if a flooding system were 
adopted by which the cold water were kept moving 
over the ground in the growing season during several 
days, the temperature of the soil might easily be 
brought so low as to seriously interfere with normal 
growth. 

The dangers, however, from using cold irrigation 
w^aters are not as great as might at first be supposed; 
and it is seldom, where good judgment is exercised, that 
the low temperature of the water of wells and springs 
need prohibit its use for the purposes of irrigation. 

In the first place, there are few cases where the 
temperature of well or spring water during the irri- 
gation season will be found as cold as 45° F., the 
more usual temperature being nearly 50° or above. 
In the second place, water warms very rapidly during 
bright summer daj^s, when spread over the surface 
of the ground, or when led along furrows, and even 
while flowing through ditches, for it absorbs the direct 
heat from the sun readily, as the rays of light pene- 
trate it, and is further indirectly warmed by the 
balance of the sunshine which, passing through the 
water, is arrested by the dark soil beneath. While 
the water is flowing over the surface of the ground, 
if its temperature is below that of the soil, it really 
stores much heat which otherwise would be lost, be- 
cause relatively much less will be lost by radiation 
from the hot surface of the soil and stored in the 
water, leaving less to pass away from the dry ground 
whose immediate surface becomes very warm, and 
hence fitted to lose heat rapidly. 



250 Irrigation mid Drainage 

In the third place, the temperature of the surface 
foot of soil in the daytime of midsummer, with its 
contained moisture, is usuall}' as high as 68° to 
75°, and to lower its temperature 1° F. requires the 
absorption by water added of from 25 to 40 heat units, 
according as the soil varies from a nearly pure sand, 
weighing 110 pounds per cubic foot, and containing 
4 per cent of water, to a humus soil, containing 30 
per cent of water and 50 pounds of dry matter per 
cubic foot. 

One heat unit is taken as the amount needed to raise 1 
pound of water at 32° to 33° F. With the relations stated, it 
appears that 4 inches of water having a temperature of 45° F. 
applied to a field having a soil temperature of 75° might lower 
the surface foot to 65° or 61.7°, according to the specific heat of 
the soil ; and with a soil temperature of 68°, the lowest tem- 
perature the 4 inches of water could produce would range be- 
tween 60° and 57.6°. But this assumes that the water is applied 
at once, with no opportunity for warming until it is brought into 
contact with the soil, which, of course, cannot be the case. If 
the irrigation water has a temperature of 50° F., then the lowest 
degree 4 inches of water could force upon the surface foot of 
soil would be some amount above 66.7° to 63.7° when the origi- 
nal soil temperature was 75°, or 62° to 59.9° if the initial soil 
temperature were 68° F. 

The results summarized on page 214 indicate that the mean 
amount of water used in single irrigations is at the rate of 2.02 
inches once in 10 days. Hence, were the coldest water used in 
this quantity, the greatest depression of the temperature of the 
surface foot could not exceed 6.7° F. This assumes that neither 
the water nor the soil receives any heat during the time the 
water is being applied. It is clear, therefore, that where good 
judgment is exercised in the application of either well or spring 
water, it may be used without in any serious way interfering with 
normal growth. The chief danger will, of course, lie in the ap- 



Fertilizing Value of Water 251 

plication of excessive amounts of water, when injury would fol- 
low certainly, and sooner than where warmer water is at hand. 

Warm water is better than cold, and in making a choice of 
waters it is, of course, best to select the warmest where this can 
be done. But the point we wish to emphasize is, that well and 
spring water and mountain streams may be used to advantage 
for irrigation where warmer water is not at hand. Mr. Crane- 
field* has experimented with tomatoes, radishes and beans grown 
in a greenhouse and in the garden, irrigated with water at 32°, 
and has found them to do nearly as well as those given water at 
70° or 100°. 

The writer waters his own garden and lawn directly from a 
well with water having a temperature of 48° to 50° F., and the 
present year we cut with a lawn mower, on 21,869 square feet 
of lawn about the house, between May 6 and November 5, enough 
grass to feed one cow all she needed for 95% days. On 90,709 
square feet, including the lawn, or 2.08 acres, we this year fed, 
by soiling, two cows and one horse from May 6 until November 
5, and put into the barn besides 4.75 tons of hay, .14 acres of 
this ground being in Stowell's Evergreen sweet corn. Three crops 
of clover were cut from the same ground, and the third cutting, 
November 1, averaged a ton of hay per acre, and was a little 
past full bloom, and yet the watering was done directly from 
the well with water at 48° F. 

FERTILIZING VALUE OF IRRIGATION WATER 

In traveling from place to place in Europe, it was 
a continual surprise to the writer to learn from those 
who were using water for the irrigation of meadows 
that the fertility which the river waters added to the 
soil was generally regarded as the chief advantage 
derived from them. The vast volumes of water which 
are sometimes used for this purpose have already been 
cited. 



*Fifteenth Ann. Rept. Wis. Agr. Exp. Station, p. 250. 



252 Irrigation and Drainage 

As an example of the amount and kind of material 
which would be added to the land where what is re- 
garded as exceptionally pure water is used, we com- 
pute from the results of analyses of the water of the 
Delaware river* the amount of material contained in 
solution in 24 acre-inches, as follows: 

Materials in 24 acre-inches of Delaware river water 

Pounds 

Calcium carbonate 242.6 

Magnesium carbonate 166.16 

Potassium carbonate IU.74 

Sodium chloride 20.54 

Potassium chloride 1.86 

Calcium sulphate 35.48 

Calcium phosphate 26.14 

Silica 93.34 

Ferric oxide 5 6 

Organic matter containing ammonia .... 117.62 

Total 741.08 

The average amounts of nitrogen compounds, as 
computed from the chemical analyses of the waters of 
twelve streams in New Jersey, are as follows: 

Nitrogen Compounds dissolved in 24 acre-inches of water from 12 
streams in Neiv Jersey 

Pounds 

Free ammonia 15.63 

Albuminoid ammonia 81.12 

Nitrates 772.67 

Nitrites .86 

Total 870.28 



*Rept. New Jersey Geol. Survey 1868, p. 102. 



Setvage Waters for Irrigation 253 

Using the figures of T. M. Read* regarding the 
amount of materials which the great rivers of the 
world bear in solution to the sea, it appears that the 
Mississippi and St. Lawrence rivers, in North America, 
and the Amazon and La Plata, in South An] erica, 
carry an amount such that the average is 655.6 pounds- 
per each 24 acre-inches of water. 

Goss and Haret, from analyses of the water of the 
Rio Grande at different periods from June 1 to Octo- 
ber 31, compute that 24 acre- inches of the water 
contained in sediment and in solution 1,075 pounds 
of potash, 116 pounds of phosphoric acid, and 107 
pounds of nitrogen. The water of this river contains 
a sufficient amount of sediment so that 24 acre- inches 
of it furnishes 81,309 pounds, or more than 4 tons 
per acre. 

It is evident from these data that the ordinary 
clear waters of rivers, lakes, springs and wells cannot 
be expected to bear to the fields upon which they are 
applied a sufficient amount of plant -food to meet the 
needs of crops, unless the water is applied in much 
larger volumes than is required to meet the demands 
of soil moisture. 

SEWAGE WATERS FOR PURPOSES OF IRRIGATION 

It may be laid down as a general rule that the 
water of highest value for the purposes of irrigation 
is the sewage of large cities, unless it contains too 

*Ain. Jour. Sci., vol. xxix , p. 290. 
tNew Mexico Expt. Sta., Bull. 12. 



254 Irrigation and Drainage 

large amounts of poisonous products from factories 
in the form of injurious chemical compounds. 

The organic matter of sewage, in both its soluble 
and finely divided, suspended form of solids, when 
sufficiently diluted with other water, is of the highest 
vahie as a fertilizer for many crops, and in all 
warm climates it is often practicable and very de- 
sirable to use such water for this purpose. 

Reference has alreadj^ been made to the use of 
sewage waters from the city of Milan on the water- 
meadows of Italy. The far-famed Craigentinny 
meadows, outside of Edinburgh, are another emphatic 
illustration of the value of sewage in the production 
of grass, and Storer, after visiting them in 1877, 
w^rites as follows : 

"In 1877 there were 400 acres of these ' forced 
meadows ' near Edinburgh, and they are said to in- 
crease gradually. The Craigentinny meadows, just 
now mentioned, were about 200 acres in extent, and 
they had then been irrigated 30 years and more. 
They were laid down at first to Italian raj^ grass 
and a mixture of other grass seed, but these arti- 
ficial grasses disappeared long ago, couch-grass and 
various natural grasses having taken their place. 
The grass is sold green to cow -keepers, and yields 
from $80 to $150 per acre. One year the price 
reached $220 per acre. They get five cuts between 
the 1st of April and the end of October. This farm 
of 200 acres turns in to its owner every year $15,000 
to $20,000 at the least calculation, and his running 
expenses consist in the wages of two men, who keep 



Setvage Waters for Irrigation 



255 



the ditches in order. The sewage he gets free. The 
yield of grass is estimated at from 50 to 70 tons 
per acre." 

In 1895, 18 years later, the writer visited the 
meadows described above, and Figs. 46 and 47 were 
taken at the time. The first figure shows a load 
of grass, estimated to weigh 2,500 pounds, cut to 
feed 23 cows during one day, from an area of 2,734 
square feet. Seven acres of this grass had been 
purchased to feed the herd of 23 cows from May 1 to 




Fig. 46. Two thousand five hundred pounds of grass cut on 2,734 sq. ft. 
of Craigentinny Meadows, Edinburgh, Scotland. 

October 20, during which time the grass would be 
cut four or five times, and the price paid for this 
grass, sold at auction, varied from $77.44 to $111.32 
per acre, according to the quality of the several plots 
making up the seven acres purchased. The increase of 
these meadows about Edinburgh, it was said, was 
tending to lower the price which this grass could 



256 Irrigation and Drainage 

command, but the superintendent informed me that 
during the past twenty years the average price per 
acre for the whole estate had been $102,20. Yet 
this grass is cat by the purchasers and hauled three 




Fig. 47. Distribution of sewage on Craigentinny meadows, Edinburgh, 
Scotland, just after cutting grass. 

to four miles day by day to feed their cows, stabled 
and milked in the crowded business portions of 
the city. 

When it is further stated that much of the land 
upon which this grass is now grown, and has been 
continuously grown for nearly a century without 
rotation, was originally a waste sandy sea beach, it 
will be the better appreciated how valuable is such 
sewage water for the purposes of irrigation. 

Regarding the healthfulness of milk produced from grass 
grown under sewage irrigation, statements like the following 
are repeatedly being made: "The only question is, whether 
there may not remain adhering to grass which has been bathed 



Sewage Water for Irrigation 257 

with sewage some germs of typhoid, cholera or other vile disease 
which are propagated in human excrement ; " and in view of 
what is now known regarding the nature of such diseases, it 
is not strange that such fears should arise in the minds of 
sanitarians. 

But in view of the fact that milk has been produced from 
such feed for nearly a century immediately within the city of 
Edinburgh, the sewaged grass traversing the streets daily during 
the whole season in sufficient quantity for several thousand cows, 
and the milk so produced wholly consumed by its people with- 
out protest, must be taken as the safest possible evidence 
that there is practically little danger in this direction ; and 
when it is remembered that the large city of Milan, Italy, has 
been supplied with milk produced from such grass fed the year 
round for more than two centuries, the evidence against the 
fear expressed is more than doubly strong, coming, as it does, 
from a warm southern climate and covering so long a period. 

The question, however, is still discussed, and in order that 
there may be no tendency to throw public vigilance off its guard 
in so grave a matter, we quote from the Edinburgh Evening 
Dispatch of July 5, 1895, parts of a discussion which was being 
had at the time of my visit, as follows: 

"Last week we called attention to the peculiar tactics 
adopted by some medical gentlemen, sanitarians and others, who 
are attempting to float a new dairy company. * * * One of 
the strategic movements of these ^philanthropic' speculators was 
to try and create a prejudice against the milk produced in the 
Edinburgh dairies, on the ground that the cows were largely 
fed on sewage grass during the summer. In regard to this, we 
pointed out that the royal commission which investigated the 
whole subject of sewage farming some years ago, reported that 
they had failed to discover a single case where injury to health 
had resulted from the use of milk drawn from cows fed on 
sewage grass. Since our article on the subject appeared last 
week, our attention has been called to some further evidence 
which fully confirms the conclusions at which the royal com- 
missioners had arrived. In his evidence given before the Rivers 



258 Irrigation and Drainage 

Pollution Commissioners, the medical officer of health for Edin- 
burgh, Dr. Littlejohn, now Sir Henry Littlejohn, said: 

" ^The cows in Edinburgh are chiefly fed with sewage grass 
that is grown on Craigentinny meadows. I have thought that 
there might be objection to feeding cows upon grass so grown, 
because I was of opinion that grass so grown might be of inferior 
quality. But practically I have failed to detect any bad effects 
resulting from the use of such grass.' 

"Another point which these philanthropic sanitarians tried to 
make out against milk from sewage -grass -fed cows was that 
such milk Uurned putrid in a very short space of time.' The 
most ample evidence is forthcoming to show the absolute ground- 
lessness of this contention also. Mr. Spier, the Scottish Dairy 
Commissioner, who has conducted most of the dairy experiments 
which have been carried on for the Highland Agricultural 
Society, has fully tested the matter, and he writes to us as 
follows on the subject: 

" ^By way of testing this point, I set aside eighteen cows for 
the experiment: Of these, six were fed in the house on sewage 
grass, six were fed in the house on vetches, and the other six 
were pastured in the fields. Milk from each of these sets of 
cows was repeatedly set aside in separate vessels until it became 
decidedly tainted, and out of the numerous tests the milk from 
the cows fed on sewage grass never once turned sour first. In 
the majority of cases, the milk from the cows fed on the vetches 
was the first to turn sour, while the milk from the sewage grass 
and on the pasture was about equal in keeping properties. On 
several occasions the milk from the three lots of cows was kept 
for the same length of time and churned separately, but on no 
single occasion did the butter from the cows fed on sewage grass 
become rancid before the other lots did. Samples of the butter 
from the three different lots of milk were sent to the chemist 
of the society, and he was unable to tell which was which. '" 

These statements will serve to call attention to the fears 
which have been expressed on theoretical considerations, and 
the nature of the evidence which appears to indicate that there 
is little ground for them. 



Value of TurMcl Water 259 

. / 

THE VALUE OF TURBID WATER IN IRRIGATION 

Next in value to warm sewage water for irrigation 
must be placed that of streams carrying considerable 
quantities of suspended solids. It is generally recog- 
nized that the richest and most enduring soils of the 
world are those formed from the alluvium of streams 
laid down by the water on its flood plains, and 
reworked many times over as the stream shifts its 
course from side to side in the valley; and when this 
is true, it will not be strange that the water of turbid 
streams has generally been held in great esteem for 
irrigation, on account of its high fertilizing value. 

In the case of the Rio Grande river, Goss has 
shown that the application of 24 inches of this water 
would add nearly one -quarter of an inch of soil to 
the field in the form of river sediment, and that this 
sediment would contain per acre 1,821 pounds of 
potassium sulphate, 116 pounds of phosphoric acid 
(P2O5), and 107 pounds of nitrogen. Four years of 
irrigation at this rate would add an inch of soil to 
the field, and 24 years would cover it 6 inches deep 
with a sediment containing three times the amount 
of potash found in the average clay soil, and the same 
percentage of phosphoric acid and a high percentage 
of nitrogen. 

When such sediments are laid down upon coarse, 
sandy soils, it will be readily appreciated that the 
gain to the field is far greater than that due to the 
mere plant -food which the sediments contain; for such 
sediments, being composed of very fine grains, their 



260 Irrigation and Drainage 

influence in improving the texture of the soil is quite ; 
as great as that due to the fertilizers contained. 

The sediment carried by the Po is given by Lom- 
bardini as toIT of the volume of the river, and on 
this account the waters are held in high esteem for 
irrigation. 

The river Nile, during the time of the rainy season 
of mountainous Abyssinia, comes loaded with sedi- 
ment constituting ittT of the volume of the water; 
and this, under the old system of the Pharoahs of 
basin irrigation, which permitted the rich mud to col- 
lect on the fields, kept them fertile for thousands of 
years, and they are so today; whereas in Lower Egypt, 
where the old practice has been abandoned in recent 
years for an "improved" system, which does not per- 
mit the utilization of the rich Nile mud, the fields are 
fast deteriorating in fertility, although only half a 
century has passed. 

The Durance, in France, is famous for its fertile 
waters, and they carry at the ordinary maximum sV of 
their weight of sediment, or nearly 1.9 pounds per 
cubic foot, equal to 82,464 pounds per each acre-foot 
of water. In rare cases the sediment of this stream 
rises to iV of the water by weight, and the average 
proportion for nine j^ears has been found to be yio". 
When such waters are used year after year on poor 
lands, the improvement becomes very great, while on 
the better lands a high and permanent degree of fer- 
tility is maintained indefinitely, with heavy yields per 
acre as the result. 



Improvement of Land hy Silting 261 

IMPROVEMENT OF LAND BY SILTING 

Nature's method of depositing the fine silt borne 
along by streams, whenever they overflowed their 
banks, early suggested the idea of directing this work 
so that the materials should be laid down on sandy 
or gravelly soils, to so improve the texture and fer- 
tility as to convert comparatively worthless areas into 
extremely productive lands. 

In other cases, where marshy, low -lying lands, or 
shallow lakes and estuaries were lying adjacent to 
turbid streams, the waters have been so turned upon 
them and then led away as to lay down mantles of 
rich soil of sufficient thickness to raise the surface to 
■such a height as to permit of di'ainage, and thus 
reclaim worthless swamps, converting them into rich, 
arable fields. 

In England, where the method was introduced 

from Italy to reclaim waste lands near the sea, the 

i process is called "warping," and in France "colmatage." 

In England, as on the Humber, where the tides rise 

several feet, and the waters of the river are turbid, 

imuch land has been reclaimed by warping. Centuries 

;ago low, flat lands were dyked off from the sea to 

{prevent inundation; but in more recent years, to 

this improvement was added the one under considera- 

ttion. Tide sluices, provided with gates to admit 

the turbid water held back by the sea, were set in 

the dykes, and the low lands were laid out in fields 

surrounded by banks for retaining the water until 

the sediment borne in upon the area should have time 



262 Irrigation ayid Drainage 

to settle, when the clear water returned to the stream 
with the fall of the tide. 

So large was the amount of sediment carried in 
the water, and so rapid was the silting -up, that fields 
of 10 to 15 acres are said to have been raised from 
one to three feet during a single season, thus convert- 
ing worthless peat bogs in so brief a time into fields 
of the richest soil. One season spent in warping, 
one for the ground to settle and become compacted, 
and a third to get it into grass, is the usual time 
requn-ed for reclamation, and after this such fields 
produce enormous crops of almost any kind suited to 
the climate. In other regions, where less sediment 
is carried in the water, or where greater depths of 
silt must be laid down in order to secure the desired 
level of the surface, longer time is required for the 
work, but in Italy fields have been raised as much 
as 6 to 7 feet in 10 years. 

In other portions of the world, notably in the 
Nile valley, a modification of this system of silting 
for the yearly enrichment of the soil is practiced. 
To this end the ancient irrigators, both in upper and 
lower Egypt, had laid out the accessible lands for 
basin irrigation, by which the turbid and fertile waters 
of the Nile, at its flood season, could be led upon the 
settling areas and held until the rich sediments were 
laid down, thus converting otherwise comparatively 
worthless sandy soils into the richest and most de- 
sirable of fields, and so maintained for thousands of 
years by periodic inundations. 

Then, again, in France, as in the Moselle valley. 



Improvement of Land hy Silting 



26e3 



and in the district of the months of the Rhone, 
between Aries and Mirimas, for example, on broad, 
flat plains of extremely coarse gravel, where in earlier 
years the uncontrolled waters have permitted no soil 
to form, this system of silting, "colmatage'' or 




Fig. 48. Head-gate on the Durance above Avignon, France. 

^'warping," has been introduced, and rich deposits 
laid down among and above the coarse materials, 
until productive fields, orchards and gardens have 
taken the place of wide reaches of naked gravel 
beds. 

Fig. 48 is a head - gate on the Durance, above 
Avignon, where a portion of the water of the district 
is taken out. The soil here, for depths exceeding 
10 feet, as shown by cuts observed, is made up, seem- 



264 Irrigation and Drainage 

ingly, of 70 per cent of coarse gravel from Xinch 
up to 4 and 5 inches in diameter, and a surprisingly 
large per cent is composed of the larger sizes. Among 
this gravel the river silt has been deposited until 
fields of alfalfa and wheat, as well as gardens and 
almond orchards, are grown upon these extremely 
pervious beds. 

OPPORTUNITIES FOR SILTING IN EASTERN 
UNITED STATES 

East of the Mississippi, extending from Wiscon- 
sin through Michigan, New York, and into New 
Jersey, as well as in New England, there are exten- 
sive areas of very sandy lands which, if they were 
subjected to this process of silting, so as to render 
them less open in texture, and to increase the per 
cent of plant -food thej^ contain, would become pro- 
ductive and very desirable lands. At present they 
are gently sloping sandy plains, bearing a scant vege- 
tation, but presenting ideal slopes for irrigation, and 
very many of which are so situated that water could 
readil}" be led upon them, both for silting purposes 
and for permanent irrigation, at relatively small cost. 

Then, again, in the southern states, notably in the 
Carolinas and Georgia, there are vast areas of sandy 
soil which stand greatly in need of such improvement 
as flooding with silt -laden waters could bring about. 
These lands possess surface features and slopes which 
readily permit of this being done ; and, what is more 
to the point, the streams are abundant and heavily 



Improvement of Land by Silting 265 

laden with silt which they are carrying out to sea in 
great volumes, thus robbing the Piedmont country at 
a fearful rate, through lack of sufficient care, of its 
most fertile soil, and transporting it directly through 
the fields to which it should be applied and upon 
which it could readily be led to great advantage. 

On the sea coasts of these three states, and par- 
ticularly in South Carolina, there lie those extensive 
and once wonderfully productive rice fields upon which 
so much labor and capital have been spent, but which 
are now largely abandoned, since the war of the re- 
bellion, for the lack of sufficient energy to bring the 
needed capital to the region. 

Here are opportunities for capital to find splendid 
permanent investment at good rates of interest, to 
reclaim the vast rice fields now fast falling into ruin, 
and to apply the methods of warping to these and 
other lands until they become what they may certainly 
readily be made, both thoroughly healthful and the 
richest of fields, adapted to a wide diversity of pro- 
ductions. The opportunities for warping are better 
nowhere in the world, and there must certainly be a 
great future awaiting intelligence, energy and capital 
here to work out the needed improvements. 

ALKALI V^ATERS NOT SUITABLE FOR IRRIGATION 

In many portions of the world, and oftenest in 
arid and semi -arid regions, the waters of some 
streams and wells, and particularly those of lakes, 
are too heavily charged with the salts of sodium — 






266 Irrigation and Drainage 

common salt, sal soda and Glauber's salt or sodium 
chloride, carbonate and sulphate respectively — to 
make it advisable to use them for the purposes of 
irrigation. 

These salts are a part of the waste products of 
soil production which ordinary vegetation is unable to 
use with profit, and which in countries of heavy rain- 
fall are washed out of the soil nearly as rapidly as 
formed. Where these salts, however, do accumulate 
to any notable extent, it is designated an alkali soil, 
and will not produce normal crops of many of the 
forms grown in plant husbandry. The general sub- 
ject of alkalies and their treatment is discussed in 
the next chapter, but we cite below the composition 
of waters which have been regarded as safe and as 
unsafe, without treatment, for purposes of irrigation: 

Table of safe and unsafe alkali waters* in parts per 1,000 





' Safe water 




' — Unsafe water — > 


No. of 
sample 


Black 
alkali 


White 
alkali 


No. of 
sample 


Black 
alkali 


White 
alkali 


740 


.022 


.067 


739 


.141 


.135 


742 


.005 


.306 


741 


.009 


8.756 


743 


.007 


.155 


753 


.026 


.818 


744 


.022 


.399 


751 


.011 


7.374 


755 


.009 


.334 


746 


.101 


1.063 


749 


.026 


.306 


747 


.115 


1.082 


750 


.014 


.111 


757 


.036 


1.577 


754 


.026 


.033 


760 


.132 


.084 



It is very unfortunate that after an analysis of a 
sample of water has shown accurately the amounts of 
various elements it may contain, it has not been pos- 



*Oomputea from Bull. 29, p. 4, Oklahoma Exp. Sta. 



I 



Alkali Water not Suitable for Irrigation 267 

sible to state with certainty precisely how these ele- 
ments were combined in the sample. It is more 
unfortnnate that chemists are not agreed as to how 
results should be interpreted, and that different sys- 
tems are followed by different analysts. But what is 
most unfortunate of all, is that many chemists have 
published their computed results, as though there 
were but one interpretation of them, and have not 
given the data upon which their computations were 
based. Hence, we have found it impossible to arrive 
at what may be regarded as the safe amount of 
black or white alkali an irrigation water may contain. 
The table given above represents the opinion of two 
chemists as shaped by their system of computing the 
amounts of the alkalies in the samples analyzed, but 
it must be understood that another chemist using the 
same data, with a different system of apportionment, 
would compute either less or more black alkali and 
more or less white alkali than the authors have 
credited the samples with as given in the table above. 

We make this explanation, that the irrigator may 
understand that when the water from a given source 
is said to contain .022 parts in 1,000 of black alkali, 
more allowance must be made in regard to accuracy 
than is required for the statement that the water car- 
ries in solution 11.234 grains of solids per gallon. 

It should be understood further, as will be shown 
in the next chapter, that a given quantity of black 
alkali may prohibit the use of the water for irrigation 
purposes on one soil, when upon another it may be 
used with perfect safety. 



268 Irrigation and Drainage 

It sometimes happens that waters draining from 
swamp lands where there has been considerable stag- 
nation, or where there are too strong solutions of 
humie acids or salts of iron, are not suitable for irri- 
gation purposes, and must be avoided. In portions 
of Europe, too, there are streams used for irrigation 
which are known as "good" streams and "bad" 
streams. Crops irrigated from one produce heavier 
yields than when irrigated from the other, and cases 
are cited where the differences in yield are so large 
that they can hardly be assigned entirely to difference 
in the amount of plant -food carried by the two. 



CHAPTER VIII 

ALKALI LANDS 
CHARACTERISTICS OF ALKALI LANDS 

The use of the term "alkali lauds," as commonly 
employed, has quite a loose or wide application. Hil- 
gard states that in California the term is applied 
almost indiscriminately to all lands whose soils con- 
tain unusual amounts of soluble salts, so that during 
the dry season or after irrigation the surface becomes 
more or less white with the deposits left by the evapo- 
ration of the capillary waters. Throughout much of 
Minnesota, Wisconsin, Michigan, and other states lying 
within the glaciated areas of this country, there are 
black marsh soils which, after being drained and 
tilled, come to acquire in spots a deposit of white 
salts at the surface whenever there is much evapo- 
ration from the soil, and these are frequently spoken 
of as "alkali spots." Where these salts are well 
marked in character, crops are killed out entirely, or 
the growth is stunted much as is true of the black 
alkali spots of arid regions. On the rice fields of 
South Carolina, there appear during the dry stage 
of growth of the crop "alum spots," as they are there 
called, upon which the rice may die out or be of 
inferior quality. Then, too, on the margins of the 

(269) 



270 Irrigation and Drainage 

sea, where there are low -lying lands periodically in- 
undated by high tides, white deposits are again left 
when the surface becomes dry, and are injurious to 
cultivated crops when they have accumulated to suf- 
ficient strength, and these are sometimes spoken of 
as "alkali lands." 

In the wide application of the term, then, "alkali 
lands" are those upon which soluble salts have ac- 
cumulated in sufficient quantity, through evaporation 
and capillarity, to attract attention by their usually 
white appearance and their injurious effects upon 
vegetation. 

Hilgard states that "alkali lands must be pointedly 
distinguished from the salt lands of the sea margins 
or marshes, from which they differ both in their 
origin and essential nature ; " and, in the sense he 
wishes to be understood, the distinction should be 
made ; but there are important advantages, as will 
appear, in treating them all under one head. 

CAUSE OF INJURIES BY ALKALIES 

When the soil water about the roots of plants or 
germinating seeds becomes sufficiently strong with 
salts in solution, the osmotic pressure is so modified 
that a discharge of the cell contents into the soil takes 
place to such an extent as to produce what is equiva- 
lent to wilting. The cells are not maintained suffi- 
ciently turgid to permit normal growth, or they may 
have the pressure so much lowered as to cause death. 
The case is like placing the plump . strawberry or 



Cause of Injuries by Alkalies 271 

currant in a strong solution of sugar, where it is ob- 
served to greatly shrink in volume. So, too, it is 
like placing meat under strong brine, and the use of 
sugar in preserves, where there is so strong a solution 
about the products preserved that the germs of decay 
cannot thrive in them. 

This, then, is one of the modes by which the in- 
jurious effects of alkalies are produced, and it should 
be understood that it matters very little what sub- 
stance may be in solution in the soil water, so long 
as it is there in sufficient quantity to produce the 
osmotic shrinkage referred to. 

Every one is familiar with the fact that too con- 
centrated fertilizers may produce death to the plant, 
and it may be by this action. Applying the principle 
to the alkalies in the soil, it must be recalled that 
these compounds are all relatively very soluble in 
water, so that if only large quantities of water con- 
taining even small amounts of the salts are evaporated 
in contact with the roots of growing crops, the so- 
lution surrounding the soil grains may become too 
strong for good plant feeding, and even death may 
result. 

On this fundamental principle of action, it is plain 
that the black as well as the white alkalies fall into 
the same category, and this, too, no matter what may 
be their composition, origin or geographic range. 

It is more than probable, if not even certain, 
that the action of some of these salts may be that of 
true poison; but the real nature of toxic effects is not 
as yet understood in any full sense. 



272 Irrigation and Drainage 

HOW ALKALIES ACCUMULATE IN THE SOIL 

Everywhere in the soil where there are sufficient 
changes in the air and the moisture, the soil grains 
are being broken down and dissolved by both physical 
and chemical means, and unless the rains are suffi- 
ciently heavy to carry the ever -forming dissolved 
salts away in the country drainage, they will be 
brought to the surface by capillarity and there con- 
centrated until precipitated. The more insoluble of 
the plant -foods, and other salts which are not such, 
cannot charge the water sufficiently high to do serious 
harm, hence in common language and in the sense 
the term is here used, they do not become "alkalies." 

But with the other salts the case is different. 
They are precipitated when the solution becomes 
strong enough, and form deposits on the surface or 
about the roots in the soil where water is being re- 
moved, but before this actually occurs one or both of 
the actions referred to above begins to take place. 

In arid regions, where the alkalies proper are most 
abundant, rains enough maj^ fall to slowly carry for- 
ward their formation, but not enough to carry them 
out of the land. From the higher levels and steeper 
slopes they are readily moved by surface drainage and 
wind action to the lower lands, where the amount 
may become so large as to form thick beds. During 
the wet season of such countries, these salts may sink 
into the soil, but to rise again when dry weather 
restores the action of capillarity. 

In the humid regions, there is necessarily an even 



How Alkalies Accumulate in Soil 273 

more rapid formation of all the true alkalies of arid 
climates; for fundamentally similar rock ingredients 
are subjected to identical weathering processes, but of 
a more intense nature, because the rainfall is greater. 
If, therefore, there occur conditions favorable to the 
accumulation of the soluble salts formed at and near 
the surface of the soil, these should be expected to 
show as alkalies. 

Most of the marsh lands of the world, excepting 
those under the influence of tide waters, owe their 
wet character to the underflow of ground-water which 
has percolated into the adjacent higher lands, and 
which rises to or near the surface w^herever this is 
sufficiently low to permit of it doing so. When such 
lands are drained, the rate of surface evaporation and 
the rise of capillary water from below may exceed 
the annual rainfall, and thus lead to an accumulation 
at the surface of salts of such intensity and character 
as to interfere with the normal growth of plants. 

It must be kept in mind that where the ground- water 
level is near the surface, the rate of capillary rise may 
many times exceed what it could be under other con- 
ditions, and since the rate of evaporation is most 
rapid where the surface soil is wettest, the conditions 
are extremely favorable for the accumulation of solu- 
ble salts at the surface of marsh lands in humid 
climates after they have been driined. The waters 
leaching through the more open, higher lands become 
charged with salts, and as these waters come again 
near the surface under the low areas they are raised 
by capillarity and evaporated, leaving the salts which 



274 Irrigation and Drainage 

had been taken up along the underground path 
to accumuhite over the low -lying lands, and since 
the evaporation of 12 inches of salt -laden Avater may 
produce more deposits than the same depth of rain 
would be sure to remove in leaching downward, the 
chances are favorable to accumulation. 

INTENSIVE FARMING MAY TEND TO THE ACCUI\rU- 
LATION OP ALKALIES 

•It has already been pointed out that during the 
growing season, after vegetation has come into full 
action, nearly all of the raius which fall in humid 
climates are retained near the surface until they are 
evaporated, either through the growing crop or from 
the soil, and since these waters tend to form salts 
when thej' are in contact with the soil grains, they 
must tend to increase the salt content near the surface. 
It is plain, too, that the heavier the crops produced 
and the greater the number of them in the season, the 
less is likely to be the loss of any water fi'oai the field 
by. under- drainage ; hence the greater the tendency 
for soluble salts to accumulate. Then, if during the 
winter season of a country the rainfall is deficient, so 
that little leaching can take place, conditions become 
still more favorable for the accumulation of alkalies. 

Further than this, if irrigation is practiced during 
the growing season only, and this water also is 
evaporated from the soil in addition to the natural 
rainfall, it is plain that the amount of soluble salts 
in the soil must increase, both on account of that ^ 
which may have been in the water applied, and that 



Amount oj Alkali Injurious 275 

which this additional water may have been instrumental 
in producing from the soil on the spot through the 
processes of weathering. 

Indeed, the more we study and reflect upon this 
problem, the more we are led to fear that in all arid 
climates, where irrigation is practiced, it will not be 
found sufficient to apply simply enough water to the 
soil to meet the needs of the crop growing upon the 
ground at the time, but, on the contrary, there must 
be enough more water applied to take up and carry 
away into drainage channels and out of the country 
to the sea not only the soluble salts which the irriga- 
tion waters carry, but also those which it causes to be 
produced from the soil aud subsoil. In other words, 
it appears that an excess of soluble salts in a thoroughly 
irrigated field is not only a normal but an inevitable 
condition, unless sufficient leaching takes place; and 
if this is true, the sparing use of water can only 
increase the number of years required to bring the 
salts up to the danger point of concentration. 

AMOUNT OF SOLUBLE SALTS WHICH ARE INJURIOUS 

IN SOILS 

Storer states that it is a matter of record that long 
experience in the south of France has shown that any 
soil which becomes visibly covered with a slight in- 
crusation of salt in times of drought is improper for 
cultivation, unless special pains are taken to prevent 
the surface from becoming dry. 

Plagniol insisted, in his time, that soils containing 
more than 2 per cent of salt are unfit for the growth 



276 Irrigation and Drainage 

of any other than samphire, saltwort, and the like, 
and that even these cannot thrive when the salt 
becomes as high as 5 per cent. 

Deherain concludes, from his studies in France, 
that while soils kept very moist may produce crops 
even when 2 per cent of salt is present, yet if the 
soils dry out badly they become sterile with no more 
than 1 per cent present. Gasparin has maintained, 
however, that while soils containing .02 per cent of 
salt may produce good crops of wheat, .2 per cent 
is more than this crop can bear. 

Speaking, next, of the alkali salts of arid climates, 
we may cite some of the data procured by Hilgard in- 
his extended and careful studies of the alkali problems 
of California. At their Tulare Experiment Station, 
he gives both the amount and the distribution of 
soluble salts in the surface 18 inches of soil where, 
in one case, barley grew to a height of 4 feet, and in 
another the amounts of the salt were so great that 
this crop would not thrive. The data which we give 
in tabular form have been read from his plotted curves, 
hence the values must be regarded as not quite exact. 

Table shotving amount and coinposiUon of alkali salts in parts per 100 
Taken September, 1894, Tulare Experiment Station, California 





Ground upon which barley 
grew 4 feet high 


Ground upon which barley 
did not grow 


Depth in Sodium 

3-in carb'ate 

sections Na.COj 


Sodium 
sulphate 

Na2S04 


Com'n 

salt 

NaCl 


Total 

soluble 

salts 


Sodium 
carb'ate 

NaoCOa 


Sodium 
sulphate 

Na-jSOi 


Com'n 
salt 

NaCl 


Total 

soluble 

salts 


to 3 in. . 


.008 


.68 


.36 


1.2 


.07 


1.22 


.68 


2.44 


3 to 6 in. . 


.009 


.26 


.07 


.34 


.1 


.16 


.1 


.38 


6 to 9 in. . 


.013 


.1 


.03 


.168 


.099 


.11 


.05 


.28 


9 to 12 in.. 


.024 


.057 


.02 


.143 


.099 


.HS 


.06 


.334 


12 to 15 in.. 


.038 


.037 


.02 


.119 


.14 


.1 


.04 


.29 


15 to 18 in.. 


.04 


.02 


.02 


.09 


.18 


.06 


.02 


.263 



Amoiivt of All'ali Injurious 



277 



Sodium nitrate is also given in these cases as a 
constituent, but as this may be regarded as a jilant- 
food, we have omitted it from the table. It will be 
observed that the total soluble salts in the surface 3 
inches where the barley grew well was about half that 
found in the case where it won Id not grow, the amounts 
in the two cases being 1.2 and 2.44 per cent of the soil. 
The difference bet wee q the amounts of the black alkali 
in the two cases stands as 8 to 70, or much more. 

Referring to the possibility of these salts interfering 
with plant life simply on account of their plasmolitic 
action, it may be said that DeVries found, as repre- 
sented in Fig. 49, that when the living cells of a plant 
were immersed in a 4 per cent solution of potassium 




2 3 

Fig. 49. Effect of too strong solution of potassiiim nitrate on the 
pT'otoplasm of plant cells. (After DeVries.) 

nitrate, there was first a shrinkage in volume through 
a loss of water, as shown between 1 and 2. When 
the solution was given a strength of 6 per cent, then, 
in addition to the change in volume, the protoplasmic 
lining P began to shrink away from the cell wall h, 
as shown at 3, and when the strength of the solution 
was made 10 per cent, the conditions shown in 4 were 



278 Irrigation and Drainage 

produced. When such conditions as those represented 
in 3 and 4 are set up, marked wilting must result and 
growth be brought nearly or quite to a standstill. 

It is not possible to state with certainty what 
strength of salt solution existed in the soil moisture in 
the cases cited above, but an approximate estimate 
may be made. Hilgard's analyses show, in the case 
of the sample from where barley would not grow, 
that the soluble alkalies amounted to 2.44 pounds per 
100 pounds of soil. If these salts were all in solution 
in the soil -water, and if the soil -water amounted to 
30 per cent of the dry weight of the soil, then the 
salts in solution would have a strength of 8.13 per 
cent. But if only 15 per cent of moisture existed in 
the soil, as might easily have been the case, and all 
the salts were in solution, then its strength would 
have been double that above, and much stronger than 
DeVries' most severe trial. It does not appear im- 
probable, therefore, that even were there no poisonous 
effect exerted upon the barley by the salts in the soil, 
the plants could not have grown, on account of the wilt- 
ing which would have resulted from the presence of 
too strong a salt solution outside the cell walls of the 
root -hairs in the soil. 

COMPOSITION OF ALKALI SALTS 

To show the character of the salts which accumu- 
late in the manner under consideration, we have 
computed the mean composition from a number of 
analyses as given by Hilgard, and the results are 
stated in the table which follows : 



Composition of Alkali Salts 279 

Table showing composition of alkali salts 

Acids and bases California Washington Montana 

Silica (SiOa) 1.663 1.552 , .42 

Potash (K2O) 3.602 9.588 1.774 

SodalNaoO) 40.058 45.387 30.442 

Lime (CaO) 519 .048 i.4b'i 

Magnesia (MgO) 258 .115 5.956 

Peroxide of iron (Fe-iO:;) nv. I alu- 
mina (AI2O3) 079 .028 .04 

Phosphoric acid (P2O5 ) 1.457 .81 .012 

Sulphuric acid (SO3) 18.946 2.12 44.482 

Nitric acid (NoOr.) 1.923 .000 1.074 

Carbonic acid (CO2) 13.982 34.058 2.208 

Chlorine (CI) 7.46 1.077 5.148 

Ammonia (NH3) 047 .000 .000 

Organic matter and water of crystalli- 
zation 11.282 5.073 8.136 

101.276 99.856 101.156 
Less excess of oxygen corresponding 

to CI 1.623 .238 1.166 

Totals 99.653 99.618 99.990 

When these results are computed as salts thej' 
stand, according to Hilgard, as expressed below: 

Table shoiving composition of soluble portions of alkali salts 

Califoi'nia Washington Montana 

Potassium Sulphate (K2SO4) 6.796 3.715 3.774 

" carbonate (KoCO^) 732 12.378 .000 

Sodium sulphate (Na2S04) 31.956 .000 61.432 

nitrate (NaNOa) 3.64 .000 1.878 

" carbonate (NasCOa) 39.413 80.053 2.94 

chloride (NaCl) 14.703 1.913 9.864 

phosphate (HNaoPOi) 2.273 1.943 .000 

Magnesium sulphate (MgSOi ) 307 .000 21 .12 

Ammonium carbonate (NH42CO3)... .157 .000 .000 



280 Irrigation and Drainage 

It will be seen from these two tables that there 
may be associated with the undesirable salts quite 
notable quantities of others which are valuable plant- 
foods. This is as should be expected, for the more 
soluble plant -foods, as well as the salts not suitable 
for plant life, must be moved by the same waters, 
and tend to collect with them. 

Hilgard points out that where the soluble phos- 
phates and considerable quantities of humus are asso- 
ciated w^th the sodium carbonate or black alkali, it is 
often desirable to first transform the sodium carbo- 
nate into sodium sulphate through an application of 
land plaster. By so doing both the humus and 
phosphates are rendered insoluble, but not unavaila- 
ble for plant -food, hence may be retained in the soil 
for future use after the alkalies, which are harmful, 
have been washed out or otherwise disposed of. This 
is an important suggestion to keep in mind. 

THE APPEARANCE OF VEGETATION ON 
ALKALI LANDS 

When cultivated crops are grown upon alkali lands, 
characteristic effects are produced which serve to point 
out the difficulty with the soil and the remedy which 
should be applied. If the salts in the soil are not too 
concentrated, the crop may germinate in a perfectly 
normal manner, but after a time begin to languish in 
spots, and remain dwarfed in stature or entirely die 
out. It is very common to see a field upon which the 
crops present an extremely uneven stand, some areas 



Appearance of Vegetation on Alkali Lands 281 

being entirely destitute of plants, or bearing only those 
which are small, while closely adjacent spots may be 
covered with large, vigorous, and perfectly normal 
growths. Fig. 50 illustrates this feature, as it is ex- 
hibited in the San Joaquin valley of California, and 
Fig. 51 shows essentially similar features as they de- 
velop on black marsh soils in Wisconsin after they have 
been tile -drained. In this latter case, the crop on the 
afflicted areas comes to an early standstill, or a plant 




Fig. 50. Vegetation on alkali lauds in California. (Hilgard.) 



may go through all the phases of growth, reaching 
maturity, but with a very dwarf habit, so that maize 
in tassel and ear may not stand higher than 6 to 10 
inches, while close by may stand another hill or group 
of them where the growth has been unusually rank 
and luxuriant. On these soils the afflicted plants pos- 
sess a very imperfect root system, the older roots 
turning brown, soft, and apparently decaying, while 
new ones form above. 



282 



Irrigation and Drainage 



DISTRIBUTION OF ALKALIES IN THE. SOIL 

The position in the soil where the alkalies may be 
found in greatest abundance varies under different con- 




rig. 51. Growth of maize on black mai-sh soil in Wisfon.sin. 

ditions. Where there is a large and prolonged, evapo- 
ration at the surface, the alkalies may be nearly all 
collected within the surface 3 or 4 inches, and hence be- 
come so strong as to do serious injury, when if this 



Bistrihution of AUali in Soil 283 

concentration had been prevented no serious harm 
could have resulted. So, too, if the salts have been 
gathered into a thin layer near the surface, heavy 
rains or an application of water by irrigation may 
move them at once bodily and nearly completely to a 
depth of 1, 2 or 3 feet, varying with the amount of 
water applied, the capacity of the soil to store w^ater, 
and the amount of water it contained previous to the 
application. Under these circumstances, it is plain 
that fields afflicted with alkalies may exhibit at one 
time the most intense symptoms of poisoning and at 
another be entirelj^ free from them, so far as revealed 
by a crop upon the ground. 

In examining soils for alkalies, it is a matter of 
the utmost importance to recognize that the distribu- 
tion of them is extremely liable to be capricious, and 
that it is easy to overlook their presence by stopping 
the sampling of the soil just short of the level at 
which all of the alkalies had chanced to be concen- 
trated ; or, again, by taking a sample of the 1st, 2d 
and 4th feet, or of the 1st, 3d and 4tli feet when, ow- 
ing to the capricious distribution, all of the salts had 
been collected in the 2d or 3d foot, and thus were 
overlooked because it may have been thought not 
worth while to make a complete section of the soil 
in question. 

CONDITIONS WHICH MODIFY THE DISTRIBUTION 
OF ALKALIES IN SOIL 

If the surface of the ground is kept naked and 
compact, so that the rate of evaporation may be 



284 Irrigation and Drainage 

strong, the alkalies will necessarily be broug-ht to the 
surface and become concentrated there, hence in posi- 
tion to do the greatest harm to growing crops. 

If thorough tillage is practiced early, so that but 
little water is evaporated except that which passes 
through the roots of the crop, then the salts cannot 
become concentrated in a narrow zone, but, on the 
contrary, will be left all through the soil where the 
roots which are taking water are distributed. In those 
cases, therefore, where the general soil water is not 
too highly concentrated to permit normal growth, 
crops may prosper so long as the surface is kept 
shaded and thoroughl}^ tilled. 

It must be observed, however, and kept in mind, 
that the roots of plants cannot withdraw moisture from 
a soil without at the same time tending to concentrate 
the salts in solution in the zone where the roots do 
their feeding ; hence, that if alkali waters are being 
used for irrigation, and in the long run if the purest 
waters are being used under, conditions of no drainage, 
sooner or later the soil of the root zone must become 
so highlj' charged with the alkali salts that reduced 
yields are inevitable. 

USE OF LAND PLASTER TO DESTROY BLACK ALKALI 

Hilgard long since pointed out that in regions 
where the water contained sulphate of lime in solu- 
tion, there sodium carbonate was absent, or existed in 
such small quantities as not to be harmful to crops, and 
he early saw and recommended that where fields were 



Land Plaster for Black Alkali 285 

troubled with black alkali in not too large quantities, 
laud plaster could be used as a fertilizer, which would 
have the effect of changing the sodinra carbonate into 
the less harmful sodium sulphate, and in this way 
transform sterile lands into those which are capable 
of being worked at a profit. He clearly saw, however, 
that such a remedy was not an absolute corrective, 
but rather of the nature of a substitution of a lesser 
for a greater evil, as, sooner or later, the sodium sul- 
phate comes to be too strong to be endured. 

Hilgard has further pointed out that the application 
of land plaster to a soil rich in sodium carbonate very 
greatly improves the texture or mechanical condition 
of such a soil, because black alkali tends to break 
down the granular structure of clay soils, and thus 
puddles them and renders them nearly uninhabitable 
by most plants, largely on account of their bad 
mechanical condition. 

Still further has Hilgard pointed out that the pres- 
ence of black alkali in a soil -water tends to dissolve 
the huniic nitrogen and the comparatively insoluble 
phosphates of the soil, so that if leachiug is taking 
place under the influence of a water containing much 
sodium carbonate, great harm is being done by depriv- 
ing the soil of two of its most important ingredients 
of plant -food. Hence if alkali lands are to be im- 
proved by drainage, this should not be done until 
steps have been taken to first transform the sodium 
carbonate to the sulphate, and thus precipitate the 
huQiic nitrogen and the phosphate so that these may 
be I'etained. 



286 Irrigation and Drainage 

KINDS OF SOIL WHICH SOONEST DEVELOP ALKALI 

Where alkali waters are used for purposes of irri- 
gation, and where sweet waters are being used under 
conditions of little or no drainage, the clayey soils 
are the ones which soonest begin to show the bad 
effects of concentrated salts. This is so for many 
reasons. 

In the first place, the soils of clayey texture, as has 
been established b}'^ experiments recorded on page 201, 
are not as effective mulches as the sandy soils, hence, 
even where thorough tillage and shade are resorted 
to, there must necessarily be a larger rise of salt- 
bearing water to the surface to produce accumulation 
than is the case with the coarse, sandy soils. 

In -the second place, when water is applied to a 
sandy soil, not nearly as much remains adhering to 
the surface of the soil grains and entangled between 
them, so that it quickly spreads downward farther 
below the surface than is the case with the clay. This 
being true, it takes less water to produce effective 
drainage, and the roots of the crop spreading farther 
in the sands, the salts cannot become concentrated as 
they may in the clays. 

In the third place, since more water is held in 
contact with the soil grains of the clays, and since 
the total surface for chemical action to take place upon 
is very much larger in the clayey soils than in the 
sands, it is plain that soluble salts, including alkalies, 
may form more rapidly in one case than in the other, 
and hence, that the open, sandy soils cannot become 



Correction of Alkali Waters 287 

alkali lands except under conditions which are ex- 
tremely favorable to their formation. 

CORRECTION OF ALKALI WATERS BEFORE USE IN 

IRRIGATION 

In case an irrigation water is known to contain an 
injurious amount of black alkali, it is possible to con- 
vert this into the sodium sulphate by the use of land 
plaster in the water before applying it to the field. 

To do this in the cases where water is stored in 
reservoirs, it is possible to arrange cribs of uncrushed 
gypsum through which the water flows in entering the 
reservoir, and if this should not be sufficient to effect 
the whole change, other cribs could be built at other 
points in the reservoir and at the outlet. So, too, 
where the lateral is taken to the field, it would often 
not be difficult to arrange so that the water flowed 
through a basin, wide ditch or reservoir in which hang 
crates of gypsum, over which the water passes on its 
way to the field, or the same method may be applied 
ill the larger canals. 

If the fields upon which alkali waters must be used 
are heavy and especially likely to be injured bj^ the 
puddling process, it would seem to be much the better 
method to apply the corrective for black alkali to the 
water itself, rather than to the field, after there has 
been opportunity for some damage to be done. 

DRAINAGE THE ULTIMATE REMEDY FOR ALKALI LANDS 

If it is true that alkali salts are formed from the 
decomposition of the soil and subsoil through the ae- 



288 Irrigation and Drainage 

tion of water and air, it is only too plain that where 
conditions are persistently maintained which allow the 1 
formation of the salts withont permitting them to be 
removed by any cause whatsoever, there must come. a 
time, sooner or later, when the amounts produced and 
accumulated in the soil shall reach the degree of con- 
centration which is intolerable to cultivated crops. \ 
Under the natural conditions of rainy countries, there 
is usually a sufficient amount of leaching to permit 
the white and black alkalies to be borne away in the 
country drainage with sufficient completeness to pre- 
vent their effects attracting general attention, and if 
the same processes obtained in irrigated countries, it 
is plain that in these, too, the difficulties would not 
arise. The cou elusion is irresistible, therefore, that some 
method must be devised by which, periodically at least, \ 
sufficient w^ater is applied to irrigated fields to pick up 
and cany out of the country the soluble alkali salts 
which are fatal to cultivated crops. 

In the old-time irrigation of tlie Nile valley, the 
greater part of the land was under basin irrigation, 
and thus thoroughly washed during some fifty days 
every year. Lands not so treated were the lighter 
sandy soils near the Nile, protected by only slight 
banks from inundation, and these dykes usually gave 
way as often as every seven or eight years, so that 
they, too, were occasionally thoroughly flooded. Un- 
der this system of washing and drainage, the fields of 
the Nile were kept free from alkalies for thousands of 
years. But at the present time, when what are called 
more rational methods are being applied, but with no 



Drainage the Ultimate Remedy for Alkali 289 

attention being paid to freeing- the soil from the ac- 
cumnlation of alkalies, these salts have been concen- 
trated to so serions an extent that already many acres 
have been abandoned. 

The probabilities are that long, long ago the same 
more rational methods (?) now being practiced had 
been tried and found inadequate or inapplicable, on 
account of the accumnlation of alkalies which they 
permitted, and the old irrigators learned to be content 
with a system which, although more wasteful in some 
ways, still kept the dreaded alkalies under control. 

It is not improbable that if the full history of 
manj^ abandoned ancient irrigation systems could be 
known, it would be found that, not being able to 
command water sufficient for drainage, or not appreci- 
ating its need, alkalies were allowed to accumulate 
until the lands were no longer productive. 

It is a noteworth}^ fact that the excessive develop- 
ment of alkalies in India, as well as in Egypt and 
California, are the results of irrigation practices 
modern in their origin and modes, and instituted by 
people lacking in the traditions of the ancient irri- 
gators, who had worked these same lands for thousands 
of years before. The alkali lands of today, in their 
intense form, are of modern origin, due to practices 
which are evidently inadmissible, and which, in all 
probability, were known to be so by the people whom 
our modern civilization has supplanted. 

The subject of Drainage will be discussed in 
Part II. 



CHAPTER IX 
SUPPLYIJSG WATER FOB IRRIGATION 

It is not the purpose in this chapter, nor has it 
been the purpose in this work, to discuss the larger 
questions of water supply for irrigation. These are 
quite purely engineering problems, involving a mass 
of detail and technicality which concern the agricul- 
turist only in the final results which they bring to 
him ; hence, he is interested in them only in a 
general way. 

We shall aim, therefore, in dealing with the supply 
of water to whole communities for purposes of irri- 
gation, to present only a general idea of the systems 
which have been evolved and adopted under the j 
var3dng conditions of different countries and climates, 
reserving the main part of the chapter for the dis- 
cussion in detail of the cases where water is supplied 
by individual effort for individual use. 

DIVERTING RIVER WATERS 

By far the most general method of supplying water for the "5 
use of large sections of country is to throw a dam across a stream, 
and divert from the channel a portion of the river water, 
leading it out into the district to be watered through canals 
provided for the purpose. 

(290) j 



Diverting Wafer from Streams 



291 



An excellent example of such a large scale system is repre- 
sented in Fig. 52, which shows the Sirhind canal, taken out of 
the Sutlej river, in the Punjab of India, at Rupar. This canal 
was designed to have a carrying capacity of 6,000 cubic feet 
per second, and extends as a single main trunk 41 miles, where 
it is bisected. Three miles further on the western trunk it is 
divided again, forming two canals of 100 and 125 miles respec- 
tively, while the eastern main branch divides into three of 90, 56 




Fig. 52. Sirhind canal system, Punjab, India. 
(Wilson, U. S. Geol. Survey.) 



and 25 miles respectively. There are in the whole system 41 miles 
of main canal, 503 miles of main branches, and 4,407 miles of 
main distributaries, supplying 800,000 acres of irrigable lands. 

The annual rainfall of the region in which this system has 
been developed varies from 10 to 35 inches. The sytem is said 
to have cost $7,831,000, and to have yielded in 1899 an annual 
revenue of 2% per cent on the cost, although less than half of 
the available land has yet been brought to use the water. 

We have already referred to the head gates of one of the 



292 



Irrigation and Drainage 



canals of the Durance, and given an engraving of it in Fig. 48. 
In further illustration of the methods used in diverting by gravity 
the water of a stream for purposes of irrigation, Fig. 53 shows 
diagrammatically how the Kern Island canal, in California, is 
taken from the Kern river, together with the position of the 
regulator, and of the waste gate by which the unused water finds 




^^^^^^ 






r^^ ^-/r .^^>i^. 






Fig. 53. Head of Kern Island canal, California. 
(Grunsky, U. S. Geol. Survey.) 

its way back into the channel. Figs. 54 and 55 are bird's-eye 
views of the same thing, showing the regulator and the waste gate. 
In Fig. 56 is given a nearer view, looking across the canal over 
the waste gate, the regulator being at the left. 

In aligning these canals, they ar^'^led back from the stream 
as far as the general fall of the valley! will permit, and in taking 
out the laterals and distributaries, these are carried to tire highest 
portions of the fields to be irrigated, and at the same time are 



Diverting Water from Streams 



293 



held as far as possible above the level of the surface, in order 
that there shall be no difficulty in taking out the water upon the 
land to which it is to be applied. 

If reference is again made to Fig. 52, it will be easy to 




Fig. 54. Bird's-eye view of head of Keru Island canal, looking up stream. 
(Grunsky, U. S. Geol. Survey.) 

understand that where such vast volumes of water are taken 
across a country in open canals, carried as high as possible and 
even above the surface, there must necessarily be an extensive 
seepage into the subsoil, which in the course of time must 
tend to raise the original ground-water level much nearer the 



294 



Irrigation and Drainage 



surface, and tend to develop swamps in the lowest -lying and 
flattest sections of the area traversed. 

It is further clear, too, that under the conditions set up by 
such a network of canals, there must be a much more rapid 




Fig. 55. Head of Keni Iskuid canal, looking down stream, 
(Grunsky, U. S. Geol. Survey.) 



action of water upon the subsoil to form alkalies ; and since, 
with the nearer approach of the ground water to the surface, the 
capillary action and evaporation must be much augmented, it 
is plain that the deterioration of land through the increase of 
alkalies is the tiling to be feared rather than wondered at. 



Diverting Water from Streams 



295 



In laying out such a system of irrigation as the one under 
consideration, it thus becomes a matter of the greatest moment 
that proper attention be paid to drainage, and that ample pro- 
vision be made for it. If this is not done, a relatively few 





Fig. 56. "Waste gate and regiiL-tior ;u lie;iil ul' Kern Island canal, looking across 
the canal. (Gnmsky, U. S. Geol. Survey.) 

years are almost certain to convert a great benefit into one of 
the most serious of scourges. Drinking waters are likely to 
become polluted, malarial fevers prevalent, and the land unpro- 
ductive, both on account of water-logging and the excessive 
accumulation of alkalies. 



296 Irrigcdion and Drainage 

The dangers in this direction will be least in countries where 
the natural drainage facilities are best ; w^here the streams, draws 
and washes are sunk deepest below the surface of the fields ; 
and where the subsoil is the most open, thus providing an easy 
escape of the seepage waters into the natural drainage channels. 
Under such conditions as these, it would be only the most waste- 
ful, extravagant and inexcusable use of w^ater, with no attention 
to proper methods of tillage, which could lead to the evils 
pointed out. 

But, on the other hand, in countries where the natural 
drainage lines are shallow and few, and where the soil and 
subsoil are close, it w^ill require the greatest vigilance and the 
rarest skill and judgment to avert the evils of swamping, the 
development of a malarial atmosphere, and the formation of 
alkalies. If, in addition to the conditions last pointed out, the 
irrigation water is naturally heavily charged with undesirable 
salts, then the situation becomes as serious as possible. 

When capital, therefore, is seeking permanent investment 
in the development of an irrigation system, the difficulties 
pointed out are matters for first and most serious consideration; 
and when agriculturists pi'opose to establish homes under such 
surroundings, the same serious attention should be given the 
probable permanency of the conditions of fruitfulness and health- 
fulness. 

It sometimes happens that water for irrigation must be taken 
from mountain canons and led out upon the mesas and over the 
valleys under great difficulties, such as tax the highest engi- 
neering skill to its utmost to accomplish. As an illustration of 
this type of irrigation engineering, the case of one of the canals 
supplying Redlands, California, may be cited. In Fig. 57 the 
dark line on the flank of the mountain on the right is an open 
canal, with ceinent masonry lining, which winds up the valley 
until it can draw its supply from the Santa Ana river. Lower 
down the mountain valley it becomes necessary to cross the canon, 
and this is accomplished by using the large redwood siphon rep- 
resented in Figs. 58 and 59. This gigantic pipe has an inside 
diameter of 4 feet, and in one portion of its course is obliged 



Redlands Irrigafiofi System 



297 



to withstand a pressure of IGO feet of water. This pipe is made 
of selected redwood staves, 2x6 inches, with edges beveled to fit 
closely, and having their ends joined by a strip of metal fitting 
tightly into a slot in the end of each stave ; the width of the 
metal strip being a little greater than the width of the stave, 




Fig. 57. ISiinta Ana canal on mountain side. 

a close joint is thus secured. The staves are bound together 
with iron hoops, whose distance apart is varied according to the 
pressure the pipe is required to withstand. 

When the canal reaches the wash of Mill creek, it is carried 
across in the flume represented in Fig. 60, also made of redwood 
staves. Further on, as the water nears its destination, one 
branch discharges its water through the paved and cement- lined 
canal into the paved and cement-lined distributing reservoir, 
both shown in Fig. 61. 

From the reservoir, the water is taken in a system of under- 




Fig. 58. Redwood pipe conveying water of Santa Ana canal 
into and out of a canon. 



Redwood Pipe Line 299 

ground cement pipes to the lands where it is to be used. These 
pipes extend beneath the surface, out of sight and out of the 
way, ranging from 14, 12, 10 and 8 inches in diameter for the 
mains, to 6 and 5 inches for the laterals ; and there were in 
1888 some 13 miles of these pipes in the Redlands settlement. 

In the general system, the lands are plotted in square 
10-acre lots, and a 5- or 6-incli lateral supplies one tier of these, 
delivering the water usually at the highest corner. These pipes 




Fig. 59. Pipe line curried on trestle. 



are generally laid on the slope of the country, which one way 
ranges from 50 to 100 feet per mile, and do not carry the water 
under much pressure, but rather more nearly as though it were 
running in open channels. The accumulation of pressure as the 
face of the country falls is prevented by the introduction of 
small concrete chambers from 5 to 6 feet square, placed at 
frequent intervals, and at the places of branching. As the water 
passes along the supply pipes it enters these chambers, rising 
until it falls over measuring weirs in the partition walls of the 
chamber, and drops into other compartments from which other 
pipes lead away in their respective directions. 




Fig. 60. Redwood stave fliinic ciirried across Mill creek wash on trestle. 






Fig. 61. Cement-liued caiuil and reservoir at Kedlands, California. 



Distrihuting Hydrants 



301 



When the water reaches the iri-igator, his delivery is made 
over a small weir, to which the water rises from below in a 
similar but smaller cement chamber, two of which are repre- 
sented in Figs. 62, 63 and 64. In Fig. 62, the water is seen 
pouring from the cement chamber or " hydrant " over a small weir 
into a distributing flume. Two other weirs in the same hydrant 
are closed by gates, and it will l3e seen that by transferring 
cither of the two gates to the weir now in use, the water would 




Fig. ()2. (Jeuieut hydrant, with weir and distributing flume. 

be turned from its present course to the one of the other two 
desired. In Fig. 63, the water is seen" flowing from the front 
weir, while the discharge is prevented from taking place into 
the compartment at the left and in the rear by the two gates 
now in place ; but in Fig. 64, the left gate has been removed 
without putting it in front, as would ordinarily be the case, so 
as to show the water pouring over that weir into its underground 
pipe for delivery in another direction. 

The system for supplying water for irrigation, now briefly 
described, and illustrated by Figs, 57 to 64, represents the high- 



302 



Irrigation and Drainage 



est type of collecting and distributing systems yet devised, and 
it is one which meets the peculiar demands brought upon it with 
almost ideal nicety. From the collecting reservoir, up in the 
mountains, behind the great Bear valley dam, the water travels 




« 



Fig. 63. Cement hydrant, with water discharging outward 
into distributing flume. 

hurriedly much of the way through closed pipes of redwood, 
steel or cement, in which all evaporation and seepage are effec- 
tually prevented, while for most of the balance of the distance 
the water glides swiftly along tight flumes and cement-lined 




Fig. 64. Same hydrant as Fig. 63, with water discharging 
over left wier into nndergrotmd pipe. 

canals of nearly faultless alignment, reaching its destination with 
so little of erosion or silting that the annual expense for mainte- 
nance is almost a trifling matter. The dangers from alkalies are 
reduced to the narrowest possible margin, and the swamping of 



304 Irrigation and Drainage 

the land is next to impossible with any rational use of water. 
When one stands upon Smiley Heights, in Redlands, and looks 
out over such panoramas of luxuriant growth as the one repre- 
sented in Fig. 65, the reflective mind is almost convinced that 
here is in reality the ultima thule in rural life. 

The cases now cited may suffice to illustrate the manner in 
which water is diverted from streams for gigantic irrigation 
enterprises, where the government itself does the work, as in 
India ; where state aid supplements the united efforts of a dis- 
trict, as in the case of the Kern river canal, and where one or 
more stock companies develop the system as a means of finding 
permanent investment for capital, as is the case with the system 
worked out to meet the needs of the Redlands district. 

It is, of course, practicable for individuals to divert portions 
of the water from streams passing through their property, pro- 
vided the fall is such as to permit of this being done, and 
where large quantities of water are to be used there is seldom a 
cheaper or more effective method of supplying water, if only 
the land and the stream are properly related for it, and the 
water is not already held by prior rights. 

DIVERTING UNDERGROUND WATERS 

In mountainous and hilly countries, where river valleys have 
become deeply filled with sands and gravels, it frequently happens 
that much of the water of the drainage basin flows below the 
surface through the valley sands and gravels, the bed of the 
channel becoming nearly or quite dry for long distances. 

In such eases, where the slope of the valley is considerable, 
and where the water has not fallen too far below the surface, 
tunnels are occasionally driven into the sands and gravels up 
the valley at a small grade until the water-bearing beds have 
risen above the line of drift sufficiently to allow the water to 
percolate into the tunnel and be led out upon the surface. 
Sometimes it is only necessary to dig open ditches, making them 
deeper up stream, to develop considerable quantities of water on 
the same principle. 



Diverting Underground Waters 



305 



Then, again, in steep valleys, where the streams carry plenty 
of water, but too far below the surface to be diverted, it fre- 
quently happens that at the foot of a terrace water may be 
flowing very near the surface toward the river channel, and by 
ditching or tunneling here this may be diverted to the surface 
when that in the river must be pumped. 

Another method of utilizing the waters which have fallen 
below the surface in the valley gravels is by building what is 
called a submerged daui across the valley, excavating to bed 




Fig. 66. Submerged dam at San Fernando, California. 

rock and erecting a water-tight dam, which shall hold the under- 
flow back until it has filled the gravels above the dam and flows 
over it at the surface high enough to be taken away in cement 
ditches, flumes or pipes to the land it is desired to irrigate. 
One such submerged dam is shown in Fig. 66, built near San 
Fernando, California. It was not, however, sufficiently well built 
to hold the water back until it could be made to overflow, and 
they were, in 1896, using two gasoline engines with pumps to 
lift the water held back by the dam, instead of depending upon 
gravity, as planned, 



306 Irrigatio7i and Drainage 



DIVEETING WATER BY TIDAL DAMMING 

Where lands bordering rivers leading to the sea lie high 
enough above low tide to admit of adequate drainage, and at the 
same time below high tide level, these may be dyked off from 
the sea, and then, by erecting sluices controlled by gates at 
suitable places in the dykes, connecting with canals and dis- 
tributaries on the land side, water may be led at will on or off 
the fields as the tides come or go. One of the most notable 
examples of this method of procuring water for irrigation is 
at the mouth of the Santee river, in South Carolina, to which 
reference has already been made, and a portion of which is 
represented in Fig. 67. 

It will be readily understood that as the tide rises along the 
coast, the discharge of the fresh water coming down the river is 
prevented and the channels fill with it, it being held there by 
the dam of salt water formed by the tidal wave. When the 
fresh water has accumulated to a sufficient extent, the trunks 
may be opened and the fields flooded, or they may be kept 
closed and the water held off. The diverting of water from 
rivers by tidal damming is only practicable where the river 
carries a sufficient volume of fresh water to prevent the salt 
water from ascending the channel, for were the volume small 
the sea would drive it back, and only salt or brackish water 
would be found against the dykes. 

DIVERTING WATER BY THE POWER OF THE 
STREAM 

Where rivers run too low in their channels to permit 
the water being led out directly, many devices have been 
employed by which a portion of the water is made to drive 
machinery which, in turn, lifts another portion out upon the 
land, where it may be led away. One of the oldest, commonest 
and simplest devices used for this purpose is the undershot 
water-wheel, set up in the stream and carrying buckets on its 



Tidal Irrigation 



307 




« ,'« « « , * * A"^ »♦*♦*»♦ ♦ , 



BOBMAY 4 CO.,ENGR'S,N.Y 



Fig. 67. Section of rice fields in Sotith Carolina. 
(U. S. Coast and Geodetic Survey.) 

circumference, which raise the water in the manner represented 
in Fig. 15, page 76. This view was taken on the river Regnitz, 
a branch of the Main, in Bavaria, where in a distance of one 



308 Irrigation and Drainage 

and one-fourth miles the writer counted no less than twenty 
such wheels. 

The wheels were 16 feet in diameter, provided with a row 
of 24 churnlike buckets on one or both sides, emptjing their 
contents into a trough, from which the water was led away in 
a flume hewn from a log. At the time the view was taken, 
this wheel was making three revolutions per minute, and dis- 
charging 450 gallons, or enough to supply nearly 120 acres with 
2 inches of water every 10 days, the water being raised 12 feet. 

On the Grand river, near Grand Junction, Colorado, the 
Smith Brothers have placed two 36 -inch turbine wheels so 
that they drive a battery of two centrifugal pumps, one above 
the other, on the same 8 -inch discharge pipe, and lift water 
82 feet, discharging it into a flume, as represented in Fig. 68, 




Fig. 68. Mouth of 8-inch discharge pipe 82 feet above Grand river, 
Grand Junction, Colorado. 

at the rate of 2,200 gallons per minute. The two wheels were 
together rated at 90 horse-power, and were developing not far 
from 54, as measured by the water lifted. They were supply- 
ing water for 80 acres of alfalfa and 120 acres of orchards, 
working only during the daytime, the water being carried a 
mile in flume and ditches. 

Other forms of water wheels, like the overshot, undershot 
and breast wheels, are used for driving centrifugal and other 
pumps to lift water for irrigation, and in large streams, where 



Lifting Water by Water Power 



309 



there is considerable fall, large amounts of water may be 
raised at a very small cost after the plant is once in place. 

Mr. F. H. Harvey, of Douglas, Wyoming, has set up a half- 
breast and undershot wheel, 10 feet in diameter and 14 feet 
long, between two wing-dams on a swinging frame, in such a 
manner as to permit it to rise and fall with the current. Being 
connected by means of a sprocket wheel and chain to the sta- 
tionary driving pulley, the changes in the position of the wheel 
with the level of the river do not disturb the action, and the 




Fig. 69. Hydraulic ramming engine. ("Wilson, U. S. Geol. Survey.) 

device runs night and day without attention, except for oiling, 
pumping 1,000 gallons per minute to a height of 16 feet, using 
a 3%- inch centrifugal pump, thus supplying more than 50 aere- 
inches per day, or enough to irrigate 200 acres at the rate of 
2.5 inches every 10 days. His plant is described as very effec- 
tive, satisfactory and, for the amount of water supplied, cheap, 
the total cost being $1,200.* 



*Bulletin No. 18, Wyoming Agr. Exp. Station. 



SIO 



Irrigation and Drainage 



The very large sizes of hydraulic rams may also be used 
on streams of relatively small fall for lifting water for the irri- 
gation of small areas, especially if used in connection with 
reservoirs. They are very simple, relatively cheap, durable, and 
require but little attention. The ramming engines, Fig. 69, are 
similar to the hydraulic rams, but are built larger and have 
greater capacities. They are more complex in structure, and 
more expensive. The engine represented in the figure is said to 
be able to elevate water to a height of 25 feet for every foot of 
fall, or to deliver one -third of the water used in its operation at 




Fig. 70. Siphon elevator. (Wilson, U. S. Geol. Survey.) 



two and one-half times the height of the fall, and one-sixth of the 
water at five times the height of the fall. Those having a drive 
pipe 8 inches in diameter and a delivery pipe of 4 inches are 
capable, under a head of 10 feet, of elevating about 6 acre- inches 
to a height of 25 feet in 24 hours, and this will irrigate 24 acres at 
the rate of 2.5 inches every 10 days. Such an engine will cost 
$500 (Wilson). 

The siphon elevator, represented in Fig. 70, is an appliance 
utilizing the principle of the hydraulic ram in connection with a 
siphon. The amount of water lifted by this varies with the dimen- 
sions of the appliance, the height to which the water is lifted, and 
the difference between the lengths of the two legs of the siphon. 
It can only be used where there is a dam, or similar condition, 



utilizing Storm Waters 311 

which permits a considerable difference between the long and 
short legs of the siphon. 

To start the action of the siphon, the long arm must be tilled 
with water ; then, as this descends again, more water rises 
through the suction arm passing into the receiver (a) and through 
the check- valve (c) into the regulator (b). In passing the check- 
valve, the drag of the water closes it, and thus stops the current ; 
but no sooner has this occurred than the momentum of the water 
opens the puppet valve (d), and a portion escapes into the 
storage tank or reservoir. While the water has been discharging 
through the puppet valve and coming to rest, the fall of water 
in the discharge arm has created a vacuum in the regulator, 
which permits the atmospheric pressure on the corrugated heads 
to force them inward and open the cheek-valve, thus starting the 
flow again. These pulsations are very rapid, ranging from 150 
to 400 per minute, so tliat a nearly continuous flow is maintained. 
Wilson states that these water elevators have been built with 
sufficient capacity to deliver 8 acre -feet in 24 hours, an apparatus 
of this capacity costing $1,200. 



UTILIZING STORM WATERS FOR IRRIGATION 

There are many sections of country where the topography is 
such as to permit storm waters to be caught by individual farmers 
in reservoirs formed by cheap earth dams thrown across the 
axis of a run, draw or ravine, and the floods produced by rains 
held back and used in irrigating lands below in times of drought. 
This is a very common practice in many parts of Europe, where 
the collected waters are oftenest used on meadows. Suitable 
arrangements are made for taking out the water, and a waste 
weir is provided by which the water may escape before the height 
of the dam has been reached. 

Where water is supplied to large districts, the use of dams 
with reservoirs is very common, especially on streams which are 
subject to large fluctuations in volume during the irrigation 
season. 



312 



Irrigation and Drainage 



'Kt.- - 




• 


^ 




4 


4M 


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B^HHflHjHB- — <^ ^B^^^ ^^P^fei^^l^Mdi^^ 


- J^- !i^^T ' -^^'^^WB 


mh| 


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hhb 


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«l 



Fig. 71. Exposiu-e of windmill which diu-ing one year pumped 79.1 
acre-feet of water 12.85 feet high. 

It will frequently happen, also, that streams or rills whose 
volume of water is too small to be used advantageously may be 
dammed and the water accumulated in reservoirs, and used by 
single individiials ; or two, three or more farmers may be located 
so as to make it mutually desirable for them to unite their efforts 
and take advantage of small streams in this way. So, too, may 
the water of springs be led out to suitable places and accumulated 
and warmed for use in irrigation. 



WIND POWER FOR IRRIGATION 

When relatively sinall areas of land are to be irrigated where 
the lift is not greater than 10 to 25 feet, and where pumps may 
be used of such forms and capacity as to economically utilize the 
full power the mill is capable of developing, wind power may be 
employed to good advantage in supplying water for irrigation. 



Wind Power for Irrigation 



313 



The writer* has conducted a series of observations with a 
16 -foot geared Aermotor windmill during one whole year, which 
shows just how much water was lifted 12.85 feet high each hour 
of every day under one set of conditions. The amount of the 
water pumped each and every hour of the day, and the number of 
miles of wind which passed the mill and did the work, were auto- 
matically recorded, giving for the first time a complete record for a 
full year of the amount of work one windmill did in lifting water. 

The mill stands on a steel tower 22 feet above the roof and 
82 feet above the ground, as represented in Fig. 71, and lifted 
the water 12.85 feet from a reservoir having an area of 285 
square feet, into a measuring tank holding 141.2 cubic feet, 
which, when filled, emptied itself in 45 seconds back into the 
reservoir. The number of times this measuring tank was filled 
each hour of the day during each month of the year, and the 
miles of wind which did the work, are given in the table on page 
315, and the results are shown graphically in Fig. 72. In this 
table the numbers at the head of the columns are the hours 



*BulIetin 68, Wis. Agr. Exp. Station. 



41)0 
iS" 
*7l>il 
*60o 

Util 
*J0O 
Hit 
4l»t 

J<?i)<) 

I3 0O 
lilO 
I IDD 
IliO 

800 

roo 









10 II xn 










- 




' 




10 


7 M 




i 


4 


i 


6 
















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) 








\ 




































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\ 


/ 
/ 










































1 














\ 


































/ 
















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— ' 


N 


/ 


N 
















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"1 


f 




N 


y 




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. — 


---. 












































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N 






































/ 


\ 


J 






s 


s 


































^ 


/ 












\j 


















































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s, 
















































S 




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Fig. 72. Upper curve shows miles of wind each hour of the year. Lower curve 
shows the number of tanks of water pumped by the same wind. 



S14 



Irrigation and Drainage 







Fig. 73. 



A B 

Aermotof 14-inch reciprocating pump used by windmill. 
A, pump ; B, piston head and suction valve. 



of the day. The lines of numbers opposite the name of the 
month express the total number of miles of wind for the hour 
of the day at the head of the column, while the other lines ex- 
press the number of times the tank was emptied during each hour 
of the day. In the footings of the table, the upper line is the 
total number of miles of wind during each hour of the day for the 
full year; the second line is the total number of tanks emptied. 



Table showing the total number of tanks of water pumped each hour of the day 

for each month, and the total rvind movement in miles for the same time. ' 



Month. 


Noon 


1. 


2. 


3. 


4i 


5. 


6. 


7. 


8. 


9. 


10. 


11. 


Mid- 
night 


March.. 


4;i5.0 


446.0 


438 


436.5 


411.0 


382.5 


378.5 


,365.5 


332.0 


323.0 


322.0 


298 


319,0 




11.?. 4 


112.8 


lll.« 


101.6 


94.5 


80.1 


61.8 


67.0 


60.3 


46.0 


62.7 


50,1 


50,9 


April ... 


.^.21.6 


512.5 


476.0 


476.0 


408.0 


4'^. 5 


392 5 


394.0 


368.0 


424.0 


431.5 


464 


412,0 




157.0 


153.8 


138.0 


137.2 


126.7 


108.2 


78.7 


74.6 


03.3 


85,8 


103.5 


108.5 


90.3 


May.... 


44(5..') 


453.5 


4,37.0 


440 5 


411.5 


361.0 


346.0 


366.5 


378.0 


373,0 


375.0 


367.0 


342.0 




115 G 


122.4 


116 2 


106.3 


93 8 


77.6 


52.7 


66.7 


68.9 


68,7 


74.5 


72.5 


73,9 


June — 


320.0 


326 5 


310.5 


320,0 


320.0 


305.5 


300.5 


292.5 


299.5 


310,0 


267.5 


267.0 


292,5 




7,'?.4 


78.0 


67.5 


66.2 


61.8 


38.0 


44.0 


48.0 


51.0 


51,0 


38.0 


47.0 


40,0 


July.... 


;r28.o 


351 :5 


347.5 


351.5 


325.5 


306,0 


273.0 


253.0 


261.5 


276.5 


258.0 


228.9 


236.5 




75.1 


71.7 


64.5 


67,7 


57.5 


.58.2 


34.7 


22.4 


23.5 


26,0 


29.2 


25.7 


29,6 


Aug 


354.0 


352 


358.0 


354 


326.0 


305.0 


282.0 


255.5 


241.0 


239,0 


247.0 


212.0 


270.5 




76.0 


79.3 


82.9 


75 4 


64.4 


54 


35.0 


35.0 


34.0 


33,0 


34.0 


38.0 


36.0 


Sept.... 


339.0 


354.0 


362.0 


351.0 


331 .0 


276 


246.0 


256.0 


271.0 


2G4.0 


272.0 


252.0 


251.0 




89.6 


101.6 


96 7 


93,1 


82.1 


49.4 


30.6 


30.3 


37.8 


37.0 


.^0.3 


38,7 


44.4 


Oct 


392.0 


401.0 


389.0 


376.0 


359 


31S.0 


341.0 


355.0 


342.0 


350 


329.0 


314.0 


325.0 




107.2 


114.1 


111 3 


103.9 


96 9 


6a. 


68.4 


83.0 


74 4 


83.3 


82.3 


72.3 


74,5 


Nov 


43(3.0 


443.0 


439.0 


425.0 


38S.0 


345 


359,0 


373.0 


368.0 


3b5-0 


373.0 


365.0 


371,0 




151.9 


l.Tj 


139.0 


136.0 


116.0 


112.0 


110,0 


114.0 


110. 


110,0 


100.0 


94 


92.0 


Dec 


395.0 


389.0 


359.0 


331.0 


326.0 


329.0 


3.34.0 


339.0 


351.0 


359.0 


348.0 


343.0 


364,0 




133.2 


119.8 


102.7 


80 


79.8 


84.3 


89.4 


84.3 


85.2 


83,0 


95.1 


105.0 


101,0 


Jan 


3S8.0 


409 


37.6.0 


356 


331.0 


317 


352.0 


362.0 


326.0 


334,0 


325.0 


306.0 


330,0 




117.5 


126.9 


113.7 


91 5 


79.1 


77.3 


85.2 


86.1 


84.4 


76.6 


71.8 


73.4 


74,1 


Feby.... 


40(5.0 


412.0 


401.0 


408.0 


381 


345.0 


365,0 


.335.0 


347.0 


363.0 


368.0 


365 


392,0 




119.2 


131 1 

48->0.fl 


1.35 


122.9 


116.4 


103.2 


99.8 


102.6 


100.9 


108.7 


106.3 


109.3 


115.1 




4741 


4693 


4625.5 


4318.0 


4026.5 


3969,5 


.3977.0 


3885.0 


4000.6 


3916.0 


3816.9 


3905.5 




1320 1 


134(i :> 


1279.3 


1181.8 


1069.0 


907.3 


79(X3 


814.0 


793.7 


809,1 


837.7 


834.5 


821.8 


Correc'n 


95.2 
1424.3 


98,5 92 1 


77 6 


67.1 


53.0 


42.2 


43.6 
857.6 


45.8 


49,0 


49,8 


49. & 


46.1 


Totals 


1445.0 1371.4 


1259.4 


1336.1 


960.3 


832.5 


839.5 


858.1 


887,5 


884,0 


867,9 


Month. 


1. 


3. 


3. 


4. 


5. 


G. 


7. 


8. 


9. 


10. 


11. 


Totals. 


March... 




354.5 


344.0 


352.0 


347.0 


433.0 


331.0 


363.5 


383.5 


410.0 


427.0 


388,0 


8765.0 






64.9 


54.9 


5S.7 


56.9 


53.3 


64.8 


75.1 


74.0 


85.1 


95.3 


84.4 


1777,1 


April.... 




414.5 
95.1 


410.0 
89.7 


4OS.0 
89 9 


410.5 
87.6 


404.0 

84.8 


429.5 
92.6 


453.5 

120.2 


410.0 

124.8 


488.5 
139.4 


493.5 
148.0 


475 
150.8 


10417 






2648.5 


May 




334.5 
73.4 


3'24.5 

68.8 


329.5 
65.6 


347.5 

77.5 


353.5 

78.8 


356.0 
76.5 


389.5 
89. G 


397.0 
104.8 


409.5 
102.4 


435.5 
96.4 


410.0 
89.4 


9472 






2035,6 


June .... 




269.0 
. 26.0 


278.5 
29.0 


275.5 
27.4 


261,5 
20.4 


269.0 
35.0 


281.0 
63.0 


353.5 
76.0 


322.5 
80.0 


310.0 
63.0 


291.5 
58.0 


297.0 
51.0 


7149 






1242.7 


July 




220.0 
27.3 


215.5 
27.0 


211.0 

18.9 


208.0 
18.0 


21S.0 
21.9 


227.0 
27.7 


247.5 
37.3 


258.0 
37.1 


286 
47.9 


311.0 
60.1 


319.5 
64.0 


6112 






973,0 


August.. 




232.0 


220.5 


243.5 


273.0 


259.0 


275.0 


239.0 


269.0 


289.5 


306.5 


298.0 


6702,0 






2G.0 


30.0 


37.2 


42.2 


31.0 


36.0 


44.0 


48.0 


57.0 


62.0 


60.4 


1150,8 


Sept 




263.0 
44.1 


265.5 
45.0 


249.5 
43.4 


255.0 
61.4 


254.0 
45.2 


261.0 
52.8 


266.0 
49.8 


258.0 
53.9 


289.0 
62.8 


310.0 
73.4 


301.0 
75.1 


6591 






1378.5 


Oct 




316.0 
72.4 


.309.0 
69.2 


307.0 
66.1 


284.0 
55.0 


265.0 
45.7 


2«8.0 
57.3 


273.0 
47.5 


312.0 
66.9 


318.0 
72.8 


351.0 
89.5 


349.0 
90.4 


7934 






1869,4 


Nov 




.372.0 


.388.0 


412.0 


408.0 


408.0 


416.0 


4IG.0 


424.0 


448.0 


434.0 


438,0 


9303,0 






102.0 


107.0 


102.0 


96.0 


95.0 


1(J8.0 


126 


129.0 


142.9 


148.9 


145,6 


2822,3 


Cec 




37S.0 


377.0 


372.0 


352 


330.0 


358.0 


3.33.0 


340.0 


349.0 


370.0 


380,0 


8557,0 






102.0 


104.5 


103 


91.6 


85.9 


99.9 


83.0 


94,1 


99.0 


115.2 


110.5 


2331,5 


Jan 




350.^ 


3.54.0 


334.0 


325.0 


339 


348.0 


335.0 


365,0 


384.0 


389.0 


374.0 


8474,0 






73 4 


76.7 


76.6 


70.0 


70.0 


83.8 


95.7 


96,2 


95.1 


111.5 


100.5 


2112,7 


Eeby 




405.0 
117.1 


396 
107,9 


419.0 
106.5 


397.0 
95 2 


384.0 
92.3 


383 

97.8 


3S4.0 
112.1 


373.0 
112.7 


390.0 
118.6 


382.0 
115.5 


348.0 
100,0 


9120 






264'6.2 




S908.5 


3S8-i.5 


,3^13 


38(58.5 


3916.5 


3953.5 


4058.5 


4112.0 


4371.5 


4.501.0 


4377,5 


98905,0' 






840.7 


809.7 


792. 3 


772.4 


738.9 


860.2 


956.3 


1021.5 


1086.0 


1173.8 


1122,1 


22988.0 


Correctio 


n*.. 


,50.8 


47.1 


44.1 


4-1.6 


40.2 


52.6 


63.5 


66.6 


72.3 


82.8 


73,9 








Totals. 


891.5 


856.8 


836.4 


814 


'779.1 


912 8 


1019.8 


1088.1 


1158.3 


1256 6 


1196.0 


24433.0 



^Approximate correction for water pumped during the time the tank was being 
emptied. 



316 



Irrigation and Drainage 



The total water pumped during the year by this windmil[ 
was enough to cover 79,1 acres 12 inches deep, thus showing an 
average daily rate of 2.6 acre -inches. The 
largest amount of water pumped on any 
single day was 39,540.2 cubic feet, or a rate 
for 24 hours of 27.46 cubic feet per min- 
ute. There were short times occasionally, 
however, when more water than this was 
pumped, but the capacity of the siphon 
was such as to cause it then to discharge 
continuously, and thus prevent a record be- 
ing made. 

Most of the water was lifted by two 
pumps, working singly or in combination. 
These were an Aermotor 14-inch reciprocat- 
ing pump, worked on a 9- inch stroke, repre- 
sented in Fig. 73, and a Seaman & Schuske 
bucket pump, with 1 -gallon buckets, as 
represented in Fig. 74. When the wind 
was light the mill was given the bucket 
pump, when stronger the reciprocating 
pump, and wlien strongest both pumps at 
the same time, and more work was ac- 
complished in this way than would have 
been possible with any single pump. 




74. Bucket irriga- 
tion pump. 



WATER PUMPED DURING 10-DAY PERIODS 



Since the availability of wind power for irrigation is limited 
not so much by the total work of the year as by the water 
which may be pumped in times of special need, a clearer idea 
of the possibilities of wind power for irrigation can be gained 
by tabulating the work done during the year by 10-day periods. 
This has been done in the table which follows, but first reducing 
the results to a lift of 10 feet instead of 12.85 feet, the height 
the water was actually raised : 



Wind Power for Irrigation 



317 



Table sJwwing computed amount of ivater lifted 10 feet high during consecutive 
10-day periods for one full year, expressed in acre-inches 



Feb. 28-iIch. 10 

JNlch. l()-20 

iMcli. 20-30 

Mc'h. 80-Apr. 9. 

Apr. 9-19 

Apr. 19-29 

Apr. 29-May9.. 

May 9-19 

May 19-29 

May 29-June8. 

June 8-18 

June lS-28 

June 28-July 8. 



Water 
pumped 



Acre-in . 
33.540 
36.620 
52.77 
47.01 
54.11 
63.05 
59.97 
28.69 
51.38 
40.54 
27 59 
13.82 
20.68 



DATE 



July 8-18 

July 18-28 

July 28-Aug. 7 . 

Aug. 7-17 

Aug. 17-27 

Aug. 27-Sept.6. 

Sept. 6-16 

Sept. 16-26 

Sept. 26-Oet. 6. 

Oct. 6-16 

Oct. 16-26 

Oct. 26-Nov. 5.. 
Nov. 5-15 



Water 
pumped 



Acre-ln 
21.53 
29.73 
9.87 
36.26 
20.20 
21.27 
18.00 
40.42 
23.79 
55.07 
18 45 
36 71 
49.49 



Nov. 15-25 . . . . 
Nov. 25-Dee. 5 

Dec 5-15 

Dec. 15-25 

Dec. 25- J an. 4 

Jan 4-14 

Jan. 14-24 

Jan. 24- Feb. 3. 

Feb. 3-13 

Feb. 13-23 .... 
Feb. 23-28 . . . . 



Water 
pumped 



Acre-in. 
52.77 
47.46 
39.52 
31.18 
51.22 
33.92 
29.16 
59.36 
33.45 
75.73 
16.20 



Referrin^^ to the table, it will be seen that the smallest 
amount of water pumped in any 10 days was 9.87 acre -inches, 
this occurring between July 28 and August 7, at a time when 
most water is needed. In this period there were 7 full days 
when no water was pumped, all the water being raised during 
3 days of the period. 

The mean amount of water pumped during the 100 days 
from May 29 to September G was 24.5 acre- inches per 10 days, 
and as this is the season in the United States when most water 
is needed for irrigation, the figure may be taken as representing 
the capacity of such a pumping system. That is to say, such a 
plant is able to supply 10 inches of water to 24.5 acres during 
100 days when the lift is 10 feet, and to 12.25 acres where the 
lift is 20 feet. If the crop irrigated demands 20 inches of water 
in 100 days, then the area which could be supplied under a 
10-foot lift would be only 12.25 acres, and under a 20-foot lift 
only 6.12 acres. It must be understood, however, that these 
results are possible only under conditions of no loss between the. 
pump and the land to which the water is applied. 

From theoretical considerations and the above data, it 
appears probable that for different sizes of wheels and for dif- 
ferent lifts, but under otherwise similar conditions, are?t§ may 
be irrigated as given in the table below. 



318 Irrigation and Drainage 

Number of acres a first-class loindmill tnay irrigate to a depth of 10 inches 
and 20 inches in 100 days 





Lift 


10 feet 


Lift 15 feet 


Lift 20 feet 


Diam. of 
wheel 


10 ins. pel 
100 days 


20 ins. per 
100 days 


10 ins. per 
100 days 


20 ins. per 
100 days 


10 ins. per 
100 days 


20 ins. 
100 da 


8.5 ft. 


2.40 


1.20 


1.60 


.80 


1.20 


.60 


10 ft. 


7.58 


3.79 


5.06 


2.53 - 


3.79 


1.90 


12 ft. 


^ 13.61 


6.81 


9.08 


4.54 


6.81 


3.40 


14 ft. 


* 17.44 


8.77 


11.70 


5.85 


8.77 


4.39 


16 ft. 


24.50 


12.25 


16.34 


8.17 


12.25 


6.13 



In computing this table for other sizes of wheels, we have 
used the ratios calculated by Wolff ; * but as our observed work 
is about 12 per cent less for the 16 -foot wheel than he com- 
putes for this size, the values in the table are correspondingly 
lower than his table would give. It is the writer's conviction, 
however, that the results he has observed for the 16 -foot 
wheel are quite as high as will be likely to be realized by 
average practice with the pumping devices of to-day. 



NECESSARY CONDITIONS FOR THE HIGHEST SERVICE 
WITH A WINDMILL 

In order that the largest service may be secured from a 
windmill, there are certain essential conditions which must be 
observed. First among these is a good wind exposure. It is 
useless to purchase a windmill and then set it up in such a 
manner that the wind cannot have free access to it. Strong 
towers, having a height of 70 to 90 feet, should usually be 
used, and these placed where hills, groves or other obstructions 
cannot break the .force of the wind. 

Second in importance to a good exposure of the mill is a 
pumping outfit thoroughly adapted to the power of the mill. It 
should not be so heavy as to force the mill to stand idle in winds 
of 9 miles per hour, and yet it should be capable of utilizing 
the full power developed in a 25- to 30 -mile wind. 



*A. R. Wolff, the Windmill as a Prime Mover. 



Wind Power for Irrigation 319 

If reciprocating pumps are used, the strokes should be made 
as long as possible and the number not higher than 20 to 25 
per minute, to avoid loss of energy in pounding. Suction and 
discharge pipes should, as a rule, be as large as the cylinder, 
and where water is to be raised above the surface, this should 
be done by carrying the discharge pipe up into the tower to 
the necessary height to avoid the use of stuffing boxes. The 
large wooden plunger rods, which displace one-half the volume 
of the water raised with each stroke, are in the direction of 
economy in making the pump in a measure double-acting. If 
a screen must be used over the end of the suction pipe, it should 
be given large capacity, and be carefully watched, to see that 
it does not become clogged. All valves should have large 
ports, easy action, and be tight fitting, so that every stroke, 
whether slow or quick, shall discharge the full capacity of the 
cylinder. 

There should be two pumps of different capacities, so arranged 
that either may be used alone, or the two used at once, thus 
providing three loads, to be applied when the wind is light, 
medium or strong. This can readily be arranged by attaching 
the lighter pump directly to the mill and the larger one to a 
walking-beam ; or both may be attached to a walking-beam, 
one end of which is carried by the driving rod of the mill. 

The geared windmills may readily be made to work a pump 
of the bucket type. Fig. 74, and if the buckets can be provided 
with valves which do not leak, a pump of large size may 
be used, speeded back so as to be driven by the mill in the lighter 
winds, and with increasing speed in the higher winds, without 
reaching the limit at which the buckets fail to empty. 

But as the power of the mill increases more rapidly than 
the velocity of the wind, what is needed is a device which 
is capable of increasing the load more rapidly also. Attaching 
an additional pump secures this end, but the objection to the 
plan is that it is not automatic, and much service must be lost 
by the mill being either too heavily or too lightly loaded until 
an attendant can make the change. Still, this plan is worth 
following until something better can be had. 



320 Irrigation and Drainage 



THE USE OF RESERVOIRS 

To employ wind power for irrigation to the best advantage, 
a reservoir is required in most eases. There are localities on 
the seashore where nearly every day a sufficient breeze springs 
up to drive the windmill, and in such cases, if the supply of 
water is large, the lift small, and the demand for water moder- 
erate, the ground for many crops may be laid out in such a 
manner that a system of rotation may be followed, and the 
reservoir dispensed with ; but in such cases the time and 
attention required for the distribution of the water will usually 
be greater than where a reservoir is used. 

The reservoir should be placed where it is high enough to 
serve all the ground to which it is desired to supply water, but 
it is very important to keep it just as low as possible, because 
since the economic lift of the mill is only 10 to 25 feet, every 
foot saved on the height of the lift into the reservoir is a large 
percentage gained in efficiency. The elevated wooden tanks, 
placed on towers far above the ground to be irrigated, are very 
expensive in themselves, and greatly reduce the area which a 
windmill can irrigate. 

In constructing a reservoir where soil and subsoil are 
reasonably fine and close, the first step is to remove from the 
area all rubbish and coarse litter that may interfere with the 
close packing of the soil. The land upon which the walls of the 
reservoir are to be built is then plowed, leaving a dead furrow 
in the center, which may be filled with water until the whole 
area is thoroughly saturated. When the water has drained 
away sufficiently to permit of teams driving over the ground, 
the soil should be thoroughly trampled and puddled, after which 
dirt from the bottom of the reservoir may be scraped on and 
trampled with the teams continuously and thoroughly. It is 
recommended as an excellent plan to maintain the sides of the 
walls higher than the center, but all portions nearly enough 
horizontal, so that water may be pumped into the furrow at 
night, to help in settling the material^ more closely and render 
the puddling more complete, , 



The Use of Reservoirs 321 

After the walls have been raised to the proper height, the 
bottom of the reservoir is plowed, harrowed fine, and the whole 
flooded with water, if practicable, to better fit the soil for 
puddling. In case the soil is at first too open for flooding all 
at once, the water may be led in furrows close together, filling 
as many at a time as the capacity of the pump will permit, 
turning the water into others when a sufiicient saturation has 
been reached. When the bottom of the reservoir has been 
thoroughly puddled over the whole area and continuous with the 
puddled bottom and sides of the walls, there will usually be but 
little loss from seepage. 

The sluice for taking out water for irrigation should be laid 
in the wall at the level of the ditch outside which carries the 
water to the fields or garden, but at some distance above the 
bottom inside, so that the water may not be entirely withdrawn 
and permit the sun to dry the soil, thus destroying the effect of 
puddling. In cold climates, it is also important to retain enough 
water in the reservoir to prevent the bottom from freezing, as 
this may destroy the effect of puddling. 

The sluice should project entirely through the walls on both 
sides, and be provided with a suitable gate or valve for closing 
and opening it, either fully or only in part, according to the 
amount of water needed, and the dimensions should be such as to 
permit more water to be taken out than is likely to be needed. 

The most thoroughly satisfactory aud permanent outlet for 
a reservoir can be provided by using wrought iron pipe of suit- 
able size, provided with an elbow at the inside, which opens 
upward. This may be closed by means of a plug worked by a 
T lever or handle, keeping the threads well protected with 
cylinder or wagon grease, to prevent rusting in. 

Oftener the sluice is made of 2-inch plank, tightly put 
together and provided with a gate, as represented in Fig. 75*. 
In other cases, the mouth of the sluice is cut off obliquely, and 
a gate is hinged to the upper side and provided with a handle 
reaching above water, to which a cord is attached for opening 



*From Bulletin No. 55, Kansas Agr. Exp. Station. 
U 



322 



Irrigation and Drainage 



the gate by simply pulling upon it. This is very simple and 
easily operated. In placing the sluice in the wall of the reser- 
voir, great care is needed to get the dirt thoroughly tamped and 
puddled about it, so that water shall not follow its sides and 
develop a leak. 

To prevent injury from waves, the walls of the reservoir 
should be sloping and not steeper inside than a rise of 1 in 2. 




Fig. 75. Sluice and gate for reservoir. (Kansas Agr. Exp. Station.) 

At the outlet ditch there should be provided an overflow weir 
sufficiently below the top of the wall to prevent wave action 
from starting a cut in the top by breaking over. A reservoir, 
completed and filled with water, is represented in Fig. 76, 
but where these are made circular in form there must be less 
seepage through the banks in proportion to the amount of water 
stored, because less wall is required to enclose a given area 
when this is circular. 



The Use of Reservoirs 323 

The amount of seepage from reservoirs must vary with the 
character of the soil, but Carpenter cites a ease where the loss 
from this cause did not exceed 2 feet for a whole year, and 
this is satisfactorily small. 

Where the soil is very open and sandy, it may be necessary 
to haul on clay or fine soil to use in puddling, or the reservoir 
may require covering with coal tar, asphalt or cement. These 




Fig. 76. Rectangular reservoir for windmill irrigation. 

materials, however, are expensive, and usually not within the 
reach of small irrigators. 

The loss of water from a reservoir by evaporation in dry, 
windy climates is much larger than the necessary seepage, and 
this can only be lessened by planting windbreaks about the 
reservoir. 

A circular reservoir 4 feet deep and 40 feet in diameter will 
supply .35 acres with 4 inches, and .69 acres with 2 inches of 
water. One, 100 feet in diameter and 4 feet deep will irrigate 
4.32 acres with 2 inches of water and 2.16 acres with 4 inches, 
while a reservoir 209 feet on a side and 4 feet deep will supply 
water enough to irrigate 12 acres with 4 inches of water, 16 
acres with 3 inches, and 24 acres with 2 inches. 



324 



Irrigation and Drainage 



PUMPING WATEK WITH ENGINES 



The amount of water whieli was pumped by a 16 -foot geared 

windmill with a lift of 12.85 foot has l)oen given as 79,1 aore- 

feet as the work of a j^ear. 

A 2% horse -power Webster gas engine was used on the same 

pumps with which the windmill did most of its work, and with 

the same lift, to see what amount of water could be supplied by 

such a power. During a 6-hours' run the engine lifted 13,202.2 

cubic feet 12.85 feet high, with a consumption of 458 cubic feet 

of gas costing $1.25 per thousand, or at a rate of 95.4 cents per 

day of 10 hours. 

At this rate of pumping and cost 

for fuel, the engine could supply in 

100 days 50,07 acres with 12 inches 

of water at a cost for fuel of $95.40 

or $1.88 per acre for the season, and 

$3.76 where 24 acre -inches of water 

is applied. 

On our own place the same make 

and size of engine as that used above, 

and represented in Fig. 77, but using 

gasoline at 9 cents per gallon for 

fuel, and lifting the water against a 

head of 50 feet with a double-acting 

pump, discharging 75 gallons per 

minute, the cost for a 96 -hours' run 

I was $4.95. 

The water pumped in this time 

was 432,000 gallons at the rate of 

Webster 23^ horse-power ^;|^ f^^, 3914 acre-inches. In 100 

vertical gasoline engine, , n -, n -i j-i- tj. u 

days of 10 hours this plant would 

lift, under its conditions, 001,605 cubic feet of water, or 13,81 

acre-feet, at a cost for fuel of $51.56, thus making the experse 

$3,73 for 12 inches in depth of water per acre, and $7.46 for 24 

inches. 




Fig. 




Fig. 78. Persian wheel for lifting watei-. (Wilsou, U. !S. (.ieol. Survey.) 




Fig. 79. Bucket pump for use with horse power. (Wilsou, U. S. Geol. Survey.) 



326 Irrigation and Drainage 

Such a pumping plant as this would easily irrigate 10 acres 
12 inches deep and 5 acres 24 inches deep without the aid 
of a reservoir, and with the aid of a reservoir the area could 
be made 15 acres or 7.5 acres, according to amount of water 
used. 

For the field irrigation on the Wisconsin Agricultural Experi- 
ment Station farm, we have used an 8-horse-power portable 
steam engine driving a No. 4 centrifugal pump. Soft coal at 
$4 per ton has been used for fuel, and with a lift of 26 feet, 
drawing the water through 110 feet of 6-inch suction pipe and 
discharging it through varying lengths of the same pipe up to 
1,200 feet, the coal consumed has been at the rate of one 
ton for an average of 80,210 cubic feet, or 22.1 acre-inches. 

At the above rate the fuel cost of an acre -inch of water is 
18.1 cents, making 12 inches of water amount to $2.17 per acre, 
and 24 inches $4.34 as the cost for fuel. 

Willcocks states that taking the mean of some 60 observa- 
tions carefully made in the delta and Upper Egypt, the actual 
discharge obtained for a 4-meter lift is 480 cubic meters per 
horse-power per 12 hours, taking the 8-horse-power engine as 
the standard, and he italicizes this statement : "J. discharge of 
4S0 cubic meters per nominal liorse-power per 13 hours is the mean 
in Egypt." 

He also estimates the cost of working a 10 -horse-power 

engine in the interior of Egypt as follows : 

£ $ 

Driver and stoker, per day 15 .73 

Oil, etc., per day 05 .24 

Coal, away from canals per day 1.00 4.84 

j^:, of 10 per cent per annum on cost of engine, 

for depreciation, repairs, etc 10 .48 

Total £1.30 $6.29 

The amount of water pumped by the 10-horse-power engine 
to a height of 13.12 feet is 3.891 acre-feet, which from the 
above table makes the cost per acre -foot $1.62 where the ground 
is covered to a depth of 12 inches, and $3.24 per acre where 
the depth is made 24 inches. 



MefJwds of Pumping 



327 




Shadoof of Egypt, or Paecottah of India. (Wilson, 
U. S. Geol. Survey.) 

Taking an average 8-liour day for pumping, the above 
pumping plant should irrigate during a 100 -day season 259.4 
acres to a depth of 12 inches and 129.7 acres to a depth of 
24 inches, at a total cost for pumping of $420.23. 



328 



Irrigation and Drainage 



THE USE OF ANIMAL POWER FOR LIFTING WATER 
FOR IRRIGATION 

Many and very old are some of the devices invented to 
utilize both human strength and that of cattle and horses. 
Fig. 78 represents the Persian wheel, very extensively used in 
Asia Minor and in Egypt for lifting water, two cattle raising 
as much as 2,000 cubic feet per day on low lifts. A more 




Fig. 81. Doon of India. (Wilson, U. S. Geol. Svu-vey.) 



modern device is represented in Fig. 79, where one horse may 
elevate through a height of 20 feet 500 cubic feet of water per 
hour and 5,000 per day of 10 hours, or a rate which, if followed 
for 100 days, would give more than 11 acres 12 inches of water 
in depth. 

Much land is irrigated in India, Asia Minor and Egypt, 
where the water is lifted by man-power, and Figs. 80 and 81 
show two of the forms of lifting devices upon which men are 
worked. Two men, working alternately, are said to irrigate an 
acre in 3 days with the shadoof, lifting the water about 4 to 6 
feet. 



CHAPTER X 

METHODS OF APPLYING WATER IN IRRIGATION 

When water has been provided for irrigation and 
brought to the field where it is to be applied, the 
steps which still remain to be taken are far the most 
important of any in the whole enterprise, not except- 
ing those of engineering, however great, which may 
have been necessary in providing a water snpply 
which shall be constant, ample and moderate in cost ; 
for failure in the application of water to the crop 
means utter ruin for all that has gone before. 

To handle water on a given field so that it shall 
be applied at the right time, in the right amount, 
without unnecessarily washing or puddling the soil or 
injuring the crop, requires an intimate acquaintance 
with the conditions, good judgment, close observation, 
skillful manipulation, and patience, after the field has 
been put into excellent shape ; and right here is 
where a thorough understanding of the principles 
governing the wetting, puddling and washing of soils, 
and possible injury to crops as a result of irrigation, 
becomes a matter of the greatest moment. There is 
great need of more exact scientific knowledge than we 
now have to guide the irrigator in his handling of 
water. 

(329) 



330 Irrigation and Drainage 

PRINCIPLES GOVERNING THE WETTING OF SOILS 

When water is applied to a soil which becomes 
more open in texture and coarser grained as the depth 
below the surface increases, it will travel downward 
in nearly straight lines, and will spread laterally but 
very little except by the relatively slow process of 
capillarity. This fact is forciblj^ illustrated in Fig. 
82, where the experiment consisted in maintaining the 
level of the water in a hole at the place designated by 
the arrow until 200 cubic feet had percolated into the 
soil. The heavily shaded area in the figure shows 
the mass of soil completely filled with water on the 
two dates, October 15 and 17, while the water was 
running. It w411 be seen that although the hole was 
kept full and the water-level within 8 inches of the 
surface, the w^ater did not spread sidew^ays more than 
2.5 feet until below a depth of 11 feet. 

If we imagine this to represent a cross -section of 
the soil under a water -furrow extending across a 
field, it will be readily seen how much w^ater would 
be lost by rapid percolation directly dow^nward, and 
how little, even after a long time, would have spread 
laterally to wet the field. To irrigate such soils satis- 
factorily and economically, the water must be spread 
over the whole surface, or be led in furrows which 
are near together across the field, so that the soil 
between the furrows may quickly become wet. 

While the water is in the furrows, it will travel 
sideways by capillarity fastest in those soils which are 
coarsest, for the same reason that it flows downward 



Principles of Wetting Soil 



331 



fastest ; namely, because the pores are largest and 
offer less resistance to the flow. The truth of this 
statement will be readily apprehended by studying 
Fig. 83, which shows how greatly the diameter of the 



SURFACE 




Fig. 82. Slow rate of lateral spread of water in soil. 

waterways in a soil is modified by the size and ar- 
rangement of the soil grains. This being true, it is 
plain that water should be moved most rapidly over 
the coarsest soils, in order that unnecessary waste by 
deep percolation may not take place. 



332 



Irrigation and Drainage 



If a soil decreases in fineness of texture as the 
depth increases, then there may be a considerable 
lateral spreading of the water due to gravity, and 




Fig. 83. Size and arrangement of soil grains as influencing pore space 
and capillary waterways. 

this, aided by capillarity, will permit the furrows to 
be placed farther apart and the water to be run more 
slowly over the ground. 

Where a fine, loamy soil is underlaid at 3 to 5 feet 
with a subsoil of much finer texture, through which 
the water percolates slowlj-, then water may be led 
quite rapidly through furrows some distance apart and 
considerable quantities applied at once, depending 
upon it to spread laterally by gravity, and to rise by 
capillarity under the spaces between the furrows, in 
this way wetting the larger part of the soil of the 



Principles of Wetting Soil 333 

field by a sort of sub -irrigation, which should be 
utilized to the fullest extent possible, for then the 
intervals between irrigations may be longest and the 
duty of water will be highest. 

If the soil is allowed to become very dry before 
watering, especially if the texture is close and the 
grains fine, water will percolate downward less 
rapidly, and it will move sideways and rise under the 
influence of capillaritj^ more slowly, because the air of 
the soil must be displaced ahead of the water. 

A fine soil, flooded under these conditions, will 
take water very slowly, because the surface pores be- 
come filled with water, which is retained with so 
mnch force that air bubbles cannot readily rise through 
it, and the conditions are similar to a jug filled with 
air bottom upwards under water, — the one cannot 
escape nor the other enter. Such soils, therefore, 
which must be flooded should not be allowed to reach 
this dry condition. The case is not so bad when 
furrow -irrigation is practiced, because the water pres- 
sure in the furrow maj- displace the air laterally 
where it can escape upward between the furrows 
unhindered by the water. 

On the other hand, there are conditions when it is 
desirable to take advantage of this hindrance of air 
to percolation. Where a clover, alfalfa, grass or grain 
field must be watered by flooding, and where the head 
of water is small, the fall slight, and the distances 
the water must be led long, the spreading will be 
much more rapid and better when the surface soil has 
become dry. Indeed we have repeatedly tried to 



334 Irrigation and Drainage 

water a certain piece of land when the surface soil 
was yet quite moist, and found it impossible to do so 
with the available head, because the water would sink 
into the ground faster than it could be supplied ; but 
by letting the soil become dryer the same head spread 
the water easily over the whole area, wetting it 
evenly, though there was greater hindrance from the 
clover having become thicker and larger. 

In furrow irrigation, the same principle may be 
taken advantage of in cases where the rows are long 
and the head of water too small, though not to the 
same extent ; but the difference is sufficiently pro- 
nounced to be sometimes quite helpful in open soils. 

PRINCIPLES GOVERNING THE PUDDLING OF SOILS 

A puddled soil is one in which the compound soil 
kernels or crumbs have been broken down more or 
less completely into separate grains and run together 
into a closely compacted mass. Such a soil may hold 
its pores between the grains so completely filled with 
water until lost by evaporation that little free air 
is present except that absorbed in the water itself. In 
such a soil roots quickly suffer for lack of air, the 
process of nitrification cannot go on, and, what is 
even worse, the nitrates alreadj" present in the soil 
when the puddling occurred may be rapidly lost by 
the process of denitrification. 

The water -logging of a soil has the same dis- 
astrous effects regarding the roots of plants and on 
the processes of nitrification and denitrification. Both 



The Puddling of Soils 335 

conditions should, therefore, be studiously avoided by 
every irrigator. 

If soils to be irrig'ated contain black alkali, and 
this has been permitted to accumulate at the surface 
during the interval between waterings, it is evident 
that the flooding of such soils will redissolve the 
alkali, and as this, in solution, tends of itself to pro- 
duce puddling, it is evident that the irrigation of 
such lands should always be done with the greatest 
care, in order not to complicate the difficulties of the 
crop by adding that of a puddled soil to the dele- 
terious action of the carbonate of soda. 

It is extremely difficult to completely submerge 
a recently stirred soil of any kind without breaking 
down the crumb structure so essential to perfect tilth, 
and all are familiar with the fact that there is no 
way to so effectually compact loose soil in a trench 
as to completely fill it with water. It is, therefore, 
plain that soils should be watered before plowing 
and fitting, when the running together cannot take 
place, rather than after the ground is seeded. Indeed, 
water enough should always be present in a soil at 
seeding time, not only to germinate the crop, but to 
carry it well on in growth, so that if baking of the 
soil must take place, less harm will be done. There 
are few soils which it would be safe to flood just 
after a crop like oats, wheat or barley is up, for fear 
of packing the soil and seriously injuring the crop. 

When the plants have attained some size, when 
the soil has gained in firmness by the natural pro- 
cesses of settling, and when the roots have spread 



336 Irrigation and Drainage 

and occupied the soil, the shading, the firming and 
the root binding all conspire to prevent puddling 
and baking, so that flooding may then be practiced 
with less danger of harm ; and so grass lands, alfalfa 
and clover may always be flooded with little danger 
of injuring the texture of fhe soil, because the exten- 
sive root systems prevent it. 

Wheu water is applied in furrows without wash- 
ing, so that it rises and spreads through the soil 
between the furrows by capillarity, it then has the 
opposite effect from puddling, and tends rather to 
improve the texture by drawing the loosened soil 
grains together into clusters by an action of surface 
tension like that which rolls drops of water into spheres 
on a dusty floor. As the soil crumbs become satu- 
rated with capillary w^ater the loose dust particles which 
have been formed in tilling are drawn to them and 
bound closely by the pull oc the surface film ; but 
so soon as the whole soil becomes immersed in water, 
as in the case of flooding, and as happens in the bottoms 
of the furrows, there is then no surface tension, and 
the soil grains fall apart under the water of their own 
weight, and compacting and puddling are the results. 

It follows, therefore, that all crops where the 
ground is not covered by them, and where cultivation 
is resorted to to i^revent loss of water by evaporation, 
should so far as pi'acticable be irrigated by the fur- 
row method ; and since the bottoms of the furrows 
must be subjected to the conditions which puddle, 
it follows that the furrows should always be as far 
apart as other conditions will permit. 



The Washing of Soils 337 

PRINCIPLES GOVERNING THE WASHING OF SOILS 

One of the commonest mistakes of beginners in 
irrigation is the use of too large volumes of water 
in a place and hurrying it over the ground too 
rapidly. It must be kept ever in mind, in all sorts 
of irrigation, that the eroding and transporting power 
of water increases with the velocity with which it 
moves, but in a higher ratio ; to double the rate at 
which water moves in a furrow or over the surface, 
increases its power to wash and carry the soil for- 
ward nearly fourfold. 

In good irrigation, the water is forced to move 
so gently that it runs nearly or quite clear and with- 
out washing the sides or bottom of the furrows, and 
if one does not succeed in securing flows without 
washing, the only conclusion which should be drawn 
is that the right way has not yet been learned, not 
that it cannot be done. 

Naturally, the steeper the slope of the furrows 
the faster the water tends to run. So, too, when the 
slope remains the same, the larger the volume of water 
in the furrow the faster the water will flow, and these 
two principles give the irrigator nearly complete con- 
trol of the situation. 

If the ground is flat and the water moves too 
slowly, increase the amount in the furrow, and if 
there is not water enough to do this, decrease the 
number of furrows handled at one time. If the water 
runs too fast and washes, divide up the stream, lead- 
ing it into more furrows until the movement comes 



338 Irrigation and Drainage 

to be the rate which does not wash or erode. We 
have seen orchards in the footliills of California irri- 
gated by carrying the water in furrows down the hill 
where the slopes were too great to readily plow with 
a team and jQi it was done with such skill that no 
appreciable wash was produced, neither did any water 
run to waste. Everything was adjusted with such 
nicety that by the time the streams had reached the 
ends of the furrows the whole of the water had been 
absorbed by the soil. The 30 acres referred to were 
owned and managed by a Swede, and w^ien he was 
asked if he did not find it difficult to handle the water 
so as not to wash his soil and waste the water on 
these steep hills, with no grading or terracing, the 
reply was : " Easy now ; but was very hard when I 
didn't know." 

The most essential point in the distribution of 
water is to have the furrows on a nearly uniform 
slope, so that the velocity of flow will be closely 
uniform through their entire length. If the same 
grade cannot be secured throughout, jt is better to 
change from a steeper slope to one more flat than 
the reverse, because then the reduction in velocity 
will be partly made up by a greater depth of water 
in the furrow on the flatter reaches. 

FIELD IRRIGATION BY FLOODING 

When large areas of land are to be irrigated ii 
single blocks, there is no method of applying water 
which is so economical of labor and of time as the 



340 Irrigation and Drainage 

systems of flooding, whenever it is possible to estab- 
lish and maintain the best conditions for them, and 
there is no other system which permits of so uni- 
form a wetting of the surface. 

There are two fundamentally different systems of 
flooding. One covers the surface of a field with a 
thin sheet of running water, maintained until the 
desired saturation has been reached ; the other covers 
the surface with a sheet of standing water, which is 
allowed to remain until the soil has absorbed enough, 
when the balance is drawn off ; or, simply as much 
water as is desired is placed upon the land, and this 
remains on the surface until it is absorbed. 

The two systems are used most for crops like 
the small grains, grasses and clovers, which closely 
cover the ground, and where intertillage is not practiced. 
They are also used extensively where fields for any crop 
must be moistened preparatory to plowing and seeding. 

Flooding by running water is practiced with great 
nicety and thoroughness on large fields of 40, 80 and 
even 160 acres in the old Union Colony at Greeley, 
Colorado. Here, usually, the natural slope of the 
country is good, and a distributing ditch is carried 
along the highest edge of a field to be irrigated. 
When the time for watering has arrived, the field is 
divided into lands of 60 to 120 feet by parallel fur- 
rows, made by using a wide V-shaped plow, throwing 
the earth both ways, thus forming distributing fur- 
rows, represented in Fig. 84, about 30 inches wide at 
the top. These furrows are made rapidly with a 3- 
or 4 -horse team, and when a crop of grain is ready 



Field Irrigation hy Flooding 



341 



to cut, a common plow is driven up one side and 
down the other of the furrow, thus filling it and 
leaving the field in shape to be driven over with the 
harvesting machine. The ridge of earth on each side 
of the distributing furrow serves the purpose of 




Fig. 85. Canvas dam taken up. 

borders to the lands, which prevent the return of 
the water to the furrows after it has been thrown 
out by the dam, shown at the point where the man 
stands in the cut. 

This dam is simply a piece of canvas tacked by 
one edge to a strip of wood 2x4 inches in thick- 
ness and 6 or 8 feet long, as seen in Fig. 85. 



342 Irrigation and Drainage 

When in use, it is laid in the furrow with the canvas 
up stream and the free edge loaded with earth to 
hold it down, when it effectually holds back the water 
and throws it out upon the strip to be watered. 

Water is turned into one, two, three or more of 
these distributing furrows from the head ditch, 
according to the amount available, and when the 
lands have become sufficiently wet as far below the 
canvas dams as the water will readily flow through 
the grain or grass, these are picked up and moved 
farther down and the stream again turned out. 
Water is thus led over successive lands until the 
whole field has been irrigated easily, rapidly, cheaply 
and, at the same time, well. 

Where crops are grown in short rotation on a 
large scale, as they are at Greeley, wheat, alfalfa or 
clover and potatoes following one another in regular 
order, it is doubtful if a better or more satisfactory 
system of irrigation can be devised than the one 
described. 

If the slopes of the field are steep, and especially 
if they incline in various directions, then the small 
grains and grasses may sometimes be irrigated better 
by the method rej^resented in Fig. 86, where water - 
furrows are thrown across the surface of the slope 
nearly along contour lines, giving them only so much 
fall as is needed to lead the water forward. 

These furrows for grain fields, where they are tem- 
porary, would be best formed with the ordinary plow, 
at the time of seeding, and the upturned earth 
smoothed down, so that it may become set before the 



Field Irrigation by Flooding 



343 



water must be led across it. Where help is scarce 
and the price of the crop small, it is often the prac- 
tice to enter the field with the plow just before the 
water is to be applied, and form the furrows then. 
In watering by this method, the aim is to throw 




Section ET 
A^ _ _ J B 

Fig. 86. Flooding field on steep slopes. (Grunsky.) 



the water over the lower edge of the furroAv in a 
continuous sheet or else at short intervals, to flow 
down the slope until the portion of the field within 
reach has received what is needed. To do this, 
canvas dams or temporary earth dams are used, as 



344 Irrigation and Bramage 

described above ; then, when the water is to be carried 
forward, the dams are also shifted. 

As represented in the figure, water maj^ be carried 
directly down the slope across a series of secondary 
furrows, as at C, D, D, D, and the main supply fur- 
rows ma}' be set one below another at such intervals 
as the extent of the fields and the slope of the 
.surface may demand. In the figure, a second water 
furrow is marked "supplj' and drain ditch," but if 
the best work is done in handling the water, there 
should be no surplus to drain away. 

When slopes like those under consideration are 
in permanent meadows or pastures, or if they are in 
meadows for three or more years, it will be best 
usually to give more time to shaping the furrows, 
so that washing will not occur when less attention 
is given, and so that the mower and horse rake may 
readily work over and across them. 

In European countries, where so much labor is 
done by hand, little attention has been paid to 
developing systems of applying water to fields which 
will readily permit of the use of machinerj^ as must 
be the case in this country, at least for a long time 
to come. 

Where grain fields are not very long, and where 
the slope is gentle and uniform, the water may be 
distributed from a single head ditch by simply mark- 
ing the field, after it has been sowed, with a tool 
like the corn -marker, but having runners close enough 
to give shallow farrows every 15 or 20 inches. 
These shallow furrows lead the water forward in par- 



Field Irrigation hy Hooding 345 

allel lines from which the lateral spread may be, to 
a large extent, by capillary creeping, and they guide 
the flow past minor inequalities, preventing the water 
from becoming concentrated so as to do injury 
through increase in volume and velocity and from 
running around areas, leaving them dry. This mark- 
ing is so rapidly and cheaply done, and obstructs 
the surface so little, that it is to be highly recom- 
mended where applicable. 

A corrugated roller might be used instead of the 
sliding marker to form the water lines, but this 
would have no tendency to throw the kernels of grain 
to one side, and the channels would be more obstructed 
by the plants. Neither could so great a depth be 
secured, especially on heavy soils not deeply and 
recently worked. 

In the second flooding S3^stem, where the water is 
made to stand over the whole surface to any desired 
depth, the fields must be laid out in areas bounded by 
ridges or low levees, which check the flow of water 
and hold it as in a wide and extremely shallow 
reservoir. 

The size of the checks in which a field is laid out 
will be determined by its general slope, by the head 
of water available, and by the height of the levees or 
check ridges. It is desirable, for meadow and grain 
irrigation, to make the checks as large as practicable 
and at the same time to keep the ridges so low 
as not to interfere with the movement of farm 
machinery over the field. 

If the slope of the field is 6 inches in 200 feet, 



346 Irrigation and Drainage 

and it is desired to place the upper edge of each 
check under 2 inches of water, it would be neces- 
sary to construct the levees, for checks 200 feet 
square, about 10 or 12 inches high, because the water 
would be 8 inches deep on the lower edge when the 
surface was covered 2 inches at the higher side, and 
a margin of 2 to 4 inches is needed for safety 
against the water breaking across over slight depres- 
sions or against wave action. 

If the fields are to be used continuously for mead- 
ows, pastures, alfalfa, or either of these, in rotation 
with small grains or similar crops which may be best 
irrigated by flooding, it will usually be desirable to 
make the check ridges broad and flat, so that mowers 
and harvesters and even plows may readily move over 
them. They thus become permanent features of the 
field. If a 20-, 40- or 80-acre field is to be laid off 
in regular checks, this would probably be most rapidly 
and cheaply done bj^ a system of plowing in repeated 
back -furrows until the desired height of ridges is 
reached. The sizes of the checks would first be deter- 
mined, and then all the ridges extending in one 
direction formed, first at the distance apart found 
desirable, after which the field would be crossed in 
the other direction, forming in the same manner the 
other sides of the checks. 

In cases where a single plowing does not give 
sufficient height to the ridges, and in countries 
where the rainfall is sufficient to permit moderate 
crops to be grown without irrigation, the labor of 
fitting the ground in this way may be made a part 



Field Irrigation by Flooding 347 

of the regular plowing for the crops, and permitted 
to extend through a number of years, thus making 
the expense of fitting the ground for irrigation 
mainly that of fitting the land for crops. By this 
plan the field would be plowed in lands in one direc- 
tion, with the back furrows always in the same place, 
until the desired height is attained ; then these back 
furrows would be crossed to form the other sides of 
the checks, plowing in the same manner. 

In case the checks are large, the land between 
the ridges may be subdivided and plowed in the 
ordinary way, letting the back furrows and dead 
furrows alternate in position with the seasons, in the 
usual manner. There will be some finishing work 
required, especially where the check ridges cross one 
another. 

It is not, of course, necessary that the flooding 
checks shall be square. If the field has a consider- 
able fall in one direction and little or none in the 
other, the checks may be made much longer in the 
nearly level direction, and thus reduce the labor and 
inequalities in the field. 

In cases where the slopes are more or less undu- 
lating, the check ridges which are horizontal will 
necessarily follow the course of contour lines, and 
may neither cross the others at right angles nor be 
parallel with one another, but they may still be 
formed in the same manner. 

When it comes to flooding, the water may be 
taken from the head distributary and sent down first 
one tier of checks and then another, dropping the 



348 Irrigation and Drainage 

water from the first into the second and the second 
into the third, over one or more breaks or weirs in 
the dividing check ridges. If, however, the checks 
are large or very many, this plan will be unneces- 
sarily wasteful of water, and a better plan is to take 
the water down the crest between two lines of checks 
in a secondary furrow. From this furrow the water 
may be turned into the check on one side and then 
on the other, flooding by pairs down the whole line. 

In the San Joaquin valley of California, in Kern 
county, there is laid out one of the largest flooding 
systems in the world. Here are more than 30,000 
acres of alfalfa in a single solid block. The slope of 
the country ranges from 5 feet to the mile to less 
than 2. Large volumes of water are at the command 
of the company, — 30 cubic feet per second, — and so 
the checks, laid out with their level ridges on contour 
lines, have various sizes and many shapes. The 
largest checks contain 200 acres, while the average is 
about 40. The ridges are 12 to 20 inches high, with 
a maximum width at the base of 12 to 18 feet, 
broadly rounded, and all covered with the growing 
alfalfa. 

Where the period of rotation is short, and where 
crops not suited to flooding are used in the rotation, 
then narrower and temporary check ridges would be 
formed for the crops to be watered in this way. The 
smallest ridges may be rapidly made on recently 
plowed fields by using a V-shaped ridging scraper 
drawn by horses, with the open side forward. The 
spreading wings throw the loose earth into the angle, 




C I I D 

Fig. 87. Flooding field by rectangular checks. (Grunsky.) 





1 \z " -A 

» • '^^ * '^^ 

.-« t 1^ • i 



Fig. 88. Flooding field by contour checks. (Grunsky.) 



350 Irrigation and Drainage 

where it is dropped in a continuous ridge, because a 
portion of each plank is cut away at the vertex, thus 
leaving an opening which passes over the gathered earth. 
If larger ridges are desired, a wider scraper, with wide 
opening in the rear, may be followed by one of 
smaller dimensions, to complete the gathering. 

The mounted road grader may be used to advan- 
tage in forming such ridges, and it would be an easy 
matter to construct a special tool for this purpose on 




Fig. 89. Model of flooding by checks. 

the principle of the road grader, but having two 
scrapers instead of one, mounted in such manner that 
they could be set closer together or farther apart, as 
desired. 

After the earth has been gathered into ridges, this 
may be smoothed down and rounded with a light 
harrow, followed by a roller, if greater firmness is 
desired. In Figs. 87, 88 and 89 are different forms 
of flooding checks, showing how the water may be 
handled in them. 



Fitting tJie Surface for Irrigation 



351 



FITTING THE SURFACE FOR IRRIGATION 



Whichever system of flooding or other irrigation is 
used, it is very important that the smaller inequalities 
of the surface should be removed by some method of 
grading, in order that the water may spread uni- 
formly, wetting the whole area. If this leveling is 
not done, some portions of the field will receive too 
much water while other areas will receive too little or 
none at all, and hence yields far below the maximum 
will be the result. 

Various forms of leveling devices are in use, and 
Fig. 90 represents one of the best, made specially for 
this purpose, and an ordinary road grader would un- 
questionably form an excellent tool for doing this 
work. 

There are many forms of scrapers of simple con- 
struction which are improvised on the farm to meet 
the needs of the moment. One of these is a letter A 
form, made of two 2x12- 
inch plank, put together 
so as to stand on edge 
and be drawn over the 
ground weighted with 
the driver riding upon 
it. The lower edges of 
the plank may be shod 
with strips of steel or 
band iron, and thus made more durable and effective. 

Another form is represented in Fig. 91, and con- 
sists of two side runners held together by cross-bars 




Fig. 90. Shuart laud grader. 



352 



Irrigation and Drainage 



of strong plank, set at an angle and shod with steel, 
as shown. This tool is much used in France and 
Italy, and a modification of it we saw in use at 
Grand Junction, Colorado, where a pair of low wheels 



JH 






¥ 



U 



<3' 



M 



Fig. 91. Simple land grader. 



were attached to the front of the scraper on a bent 
iron axle, which could be worked by means of a lever 
to raise or lower the scraper at will, thus causing it 
to drop or take on dirt where desired. 



FIELD IRRIGATION BY FURROWS 

Where crops like maize, sorghum and potatoes are 
grown in large fields, and where intertillage must be 
practiced, it is usually best to irrigate by the furrow 
method after the crop is on the ground. In countries 



Field Irrigation hy Furrows 353 

where the soil must be prepared for planting by first 
watering, it is very important, especially with pota- 
toes, that the soil should be thoroughly saturated to a 
depth of 4 feet before fitting the ground. 

If these crops are to follow clover or alfalfa, as 
will usually be the case, the preliminary watering may 
be given in the late winter or early spring by one of 
the flooding methods, if the ground has been fitted for 
that ; but however the saturation is accomplished, the 
soil should have all it will carry at the time of fitting 
for seed, unless natural rainfall may be depended 
upon . 

After planting, frequent surface tillage to conserve 
the moisture should be practiced, and the crop carried 
forward as far as possible without irrigation. The 
harrow should follow the planter at once for both 
maize and potatoes, and frequently thereafter as long 
as the crop will bear it without injury, which will be 
after both are well out of the ground. 

Where a vigorous growth of vines can be main- 
tained by intertillage alone until they cover the 
ground and the tubers begin to set, this is by far the 
best practice for potatoes. So, too, is it best for 
nearly all crops planted in rows which permit of cul- 
tivation ; and it should ever be kept in mind that 
4 feet of good soil well saturated and well cared for 
by intertillage may easily carry 6 and even 8 inches 
of available water, and this, under good conditions, 
is far more effective than any which may be ap- 
plied later. 

When potatoes are ready to be laid by, the last 

w 



■I 



354 Irrigation and Drainage 

cultivation should be with a double -wing cultivator, 
which will form a furrow midway between the rows 
and at the same time tlii'ow the soil up under the 
vines, forming a high, broad ridge of mellow soil 
above the roots in which the tubers may set and over 
which the water should never rise. The furrows thus 
formed fit the field for irrigation. 

When the time for irrigation has arrived, which 
should be deferred as long as the vines continue to 
grow vigorously, water will be taken from the head 
ditch and subdivided between as many rows as it will 
supply, as represented in Figs. 92, 93 and 94, where 
the first one shows the canvas dam just put in place 
in a head ditch in a field near Greeley, Colorado. 
Fig. 93 shows the irrigator, with rubber boots and 
spade, opening the head ditch to let the water into 
the furrows ; while Fig. 94 shows the water 30 minutes 
later, as it is flowing between rows 40 rods long. 

It will be noted that the water has been let into 
only alternate rows, and this is a common practice 
where water is scarce. It is also a frequent practice 
where water must be taken in rotation and the time 
is too short to go over the whole field. In such 
cases, when the next turn comes the water would be 
sent down the remaining rows. 

Very great care is taken not to let in so much 
water as to fill the furrows and flood the hills, for 
it is far better to let the water rise under the hills 
by capillarity. 

In another field near the same city, two men were 
irrigating 47 acres of potatoes planted in rows 120 




Fig. 92. Canvas dam in place, preparatory to turning water into 
potato rows of Fig. 94. 




Eig, 93. Opening head ditch of Fig. 92, to turn water into rows of Fig. 94. 



356 



Irrigation and Drainage 



rods long and, from a single head ditch, sending the 
water the whole length. They were nominally using 
175 Colorado inches of water, distributing it in alter- 
nate furrows. 

Before going home at night they divided this head 
between 40 rows which had been once irrigated, 




Fig. 94. Irrigating potato rows 40 rods long from head ditch of Fig. 92. 



gauging the flow in each, so that, in their judgment, 
the lower ends of the furrows would be nearly reached 
on their return in the morning. After watering once 
begins, it is kept up until the crop is matured, going 
over the field every 10 to 15 days. 

In the growing of potatoes by irrigation, it is a 
matter of the greatest importance that the ground 
shall be kept well moistened continuously after the 
tubers have begun to form, so that they shall be kept 



Field Irrigation by Furrows 357 

steadily growing. If the ground is allowed to become 
dry enough to check their growth and another irri- 
gation follows, the tubers will then throw out new 
growths and become irregular in form and unsalable. 

In Colorado the potatoes are usually planted in 
rows 4 feet apart. This distance is much greater 
than is required in humid climates, and it would seem 
that were the same amount of seed planted upon 
three -fourths of the ground, or even five -eighths, 
making the rows 36 inches or 30 inches apart instead 
of 48 inches, the ground could be more thoroughly 
watered and larger yields per acre secured. 

It is certain that the practice of only watering 
alternate rows, which is common where water is scarce, 
does not permit the largest yields to be secured. It 
has been shown by studies in the humid climate of 
Wisconsin, and with only 30 inches between the rows, 
as a mean of two years' trials, that watering between 
all rows gave a yield of 317.3 bushels per acre ; 
watering between alternate rows gave 277.1 bushels 
per acre, when the natural rainfall alone gave 211.6 
bushels per acre. That is to say, the irrigation 
between all rows increased the yield over the natural 
rainfall 105.7 bushels per acre, while irrigating between 
alternate rows only increased the yield 65.5 bushels 
per acre, making a difference between the two methods 
of irrigation of 40.2 bushels of merchantable tubers 
per acre. 

In these experiments the field was divided into alter- 
nating groups, which were watered and not watered, 
so that there were two rows in each irrigated plot 



358 Irrigation and Drainage 

watered on but one side, and it was the yield from 
these rows which has been used in making the com- 
parison. 

It was also found that the first row not irrigated 
on either side, and hence standing 45 inches from 
the center of the water furrow, had its jdeld increased 
by the watering onlj- 7.9 bushels per acre. This 
makes it appear that were the potatoes planted in 
rows 90 inches apart and the water applied in a single 
furrow between each two rows, the benefit derived 
from the water would be much less. 

It is very clear, therefore, that in furrow irriga- 
tion care must be taken that the water is not led 
along lines tpo distant from the plants which are 
to use it. 

Where the water is to be allowed to run some 
time in individual rows, and where considerable quan- 
tities are being handled, it will often be found desir- 
able to take it out of the head ditch into short 
feeders which supply a certain number of rows, as 
represented in Fig. 95, where the water in the fore- 
ground is in the head ditch, the feeder standing next 
sending water into 8 rows of rape, 28 inches apart 
from center to center, from which the first cutting 
has just been removed. 

Sugar beets, maize, and all field crops upon which 
intertillage is practiced would be irrigated in a similar 
manner ; but in such close planting as that above 
on sandy loams or lighter soils, it would probably 
be sufficient to lead water down every other furrow, 
keeping the other rows under frequent flat cultivation. 



Field Irrigiation hy Furrows 



359 



In Italy, where so much work is done bj^ hand, it 
is a frequent practice to throw the field for maize 
into flat ridges or beds 6 feet wide with strong irri- 
gation furrows between, planting the corn in an 
open broadcast manner on the beds, to be watered 




Fig. 'J5. Dividing water Ijetween eight rows of recently cut rape. 

by flooding through the heavy furrows. The same 
practice is followed to some extent for the small 
grains and clover also. 



WATER - MEADOWS 



Most water-meadows are laid out with the view 
of maintaining a continuous flow of water over the 
whole surface for considerable periods of time, with 



360 Irrigation and Drainage 

bat little personal attention. Large volumes of water 
are usually used, and in Europe especially this is 
applied more extensively out of the growing season 
than during it, or, more exactly stated, during times 
when the crop is off rather than when on the 
ground. 

Reference has already been made to the water- 
meadows near Salisbury, England, where Fig. 16 
shows a large part of the river Avon diverted into 
a canal to be led out for water-meadow irrigation. 
In Fig. 96 is represented a diagram of one of these 
water-meadows covering about 15 acres. The solid 
lines are permanent distributing ditches beginning in 
the head distributary and ending near the river at 
the foot of the field. They are placed about 3 rods 
apart, upon the crests of ridges which are quite 
steep, sloping from 1 in 12 to 1 in 15 feet toward 
the dotted lines, which are permanent drainage fur- 
rows. It is on this field that the photograph shown 
in Fig. 17 was taken. In talking with a "mead- 
man," whose business is to water one of these meadows, 
it appears that water has been run over them year 
after year for so long a period that no one knows 
who laid them out. The mead- man in question was 
past sixty years of age, and both his father and 
grandfather had been mead -men for the same field. 
It is quite probable, therefore, that the steep slopes 
now found have been to a considerable extent a mat- 
ter of growth due to deposit of sediments in the 
distributaries, and to some extent to erosion along 
the drainage lines. The plan of this system of irri- 



Water -Meadows 



361 



Ration is to hold the distributaries along the crests 
of the ridges full of water their whole length, so 
that it shall overflow from both sides and run down 




Fig. 96. Plan of old water-meadow, Salisbury, England. 

the slopes into the drainage ditches in a thin and 
even veil ; and in order that this shall be realized, 
the distributaries are widest at the upper end, grow- 



362 Irrigation and Drainage 

ing gradually narrower toward the foot, while the 
drainage ways increase in width toward the foot. In 
the meadow in question, the measured widths and 
depths of the distributaries at their heads were 42 
inches by 24 inches respectively, in all except Nos. 
10, 11, 12 and 13, 10 and 11 being 28 by 24, 12 
being 48 bj^ 24 inches, and 13 14 inches wide and 
12 inches deep ; but the capacity of the drainage 
ditches was only about one -fourth that of the dis- 
tributaries. 

In Italy the winter meadows, when laid out in 
what is regarded as the best manner, have sloping 
faces not wider than 25 to 30 feet, and with the crests 
12 inches higher than the hollows, while the lengths 
are quite variable, depending upon the volume of 
water at command, but usually being 8 or 10 times 
the width. The distributaries have a width of 12 
inches and a depth of 6 to 7 inches, while the drain- 
age lines have dimensions about one -half of these. 

In the summer water-meadows of Italy, the sur- 
face is much more nearly level between the distribu- 
taries, and often there is no intermediate drainage 
furrow, its function sometimes being fulfilled by a line 
of drainage tile beneath the surface. 

In the Campine of Belgium, extensive sandy plains 
have been laid out in water-meadows, and Fig. 97 
represents a small section of this system near Neer- 
pelt, where the water is distributed through canals 
on the crests of ridges, as already described, and 
in the plan the heavy lines represent the distribu- 
taries, while the lighter lines represent the drainage 



364 



Irrigation and Drainage 



system. It will be seen that the land is laid out 
so as to use the surplus drainage water over again, 
by collecting it into a foot ditch which is extended 
to a lower level in the field, where it becomes the 
head ditch, and discharges its water into another set 
of distributaries, as represented in the plan, the over- 




rig. 98. Model of field laid out for water-meadows, with slopes exaggerated. 

flow water from the upper section being used upon 
the third or lower section. The area shown in the 
plan is about 26 acres, the distance between the 
distributaries about two rods, and the crests stand 
nearly 10 inches above the troughs. In Fig. 98, there 
is represented a small piece of ground laid out upon 
this plan on a reduced scale. 

It will be seen that this system of irrigation not 
only involves a large amount of labor to fit the land, 



Iryngation of Cranberries 365 

but it throws out of use a large percentage of the 
area irrigated, while at the same time greatly inter- 
fering with the working of the ground and harvesting 
of the crops. Evidently the system is not well suited 
to American conditions where machinery is to be used. 
In the irrigated mountain meadows, such as the 
one represented in Fig. 14, the slopes of the fields 
are so steep that the water is usually led through 
irregular furrows whose direction is determined by 
the natural configuration of the ground, and the 
practice becomes a species of "wild flooding" where, 
on account of the great fall, the water is distrib- 
uted without much labor having been expended in 
shaping the surface. 

IRRIGATION OF CRANBERRIES 

Cranberries are usually grown upon very level 
lands, where the ground water is naturally at or 
very close to the surface. During the growing sea- 
son, the aim is to hold the water in the ground to 
within 18 or 24 inches of the surface, but on 
account of insect ravages and frosts, it is frequently 
imperative that the lands shall be flooded quickly 
to a depth of 6 to 10 inches, and the water drawn 
off again in a short time. To prevent winter-killing, 
it is also desirable to flood the vines and hold them 
under water until the danger from frost is past in 
the spring, and these requirements make it necessary 
to have the marshes laid out as represented in Fig. 
99, where blocks of land are surrounded by low 



366 



Irrigation and Drainage 



dykes and wide ditches, and at the same time divided 
into narrow lands of 30 to 60 feet by parallel nar- 
rower waterways, which are at once distributaries and 
drainage ditches, according as water is being applied 
or removed. These minor distributaries and drainage 
lines are made necessary chiefly by the necessity of 
rapid and satisfactory drainage after the ground has 




i 



Fig. 99. Plan for irrigation of cranberries. 



been flooded for protection against insects or frost. 
The side ditches may be 3 to 5 feet wide and 2 
to 3 feet deep, according to the size of the area 
under treatment, while the minor cross -ditches should 
be 24 to 30 inches wide and 18 to 24 inches deep. 

There are many localities where the land is suit- 
able for cranberry culture, but where running water 



Irrigation of Crmiberries 



367 



is not available for the purpose of irrigation. In 
some of these localities there are large quantities 
of water in the ground beneath the marshes, which 
could be utilized if it could be lifted cheaply. 
Where this water need not be lifted more than 10 
to 20 feet, and where there is an abundance of it 
in the ground, it will often be practicable to lay 




Fig. 100. Plan for cranberry irrigation by pumping. 

out a piece of ground in the manner represented in 
Fig. 100, with a reservoir in the center capable of 
storing water enough to flood the balance of the 
ground whenever desired, and then set up a wind- 
mill of suflacient capacity to maintain this reservoir 
full of water, letting the surplus go to the ditches 
if needed there, to hold the water up to the desired 
height for best growth. 



368 Irrigation and Drainage 

The object of placing the reservoir in the center 
of the area to be controlled is to utilize the seepage 
from the reservoir to hold up the ground water to 
the desired level more readily. A 12 -foot steel mill 
should readily handle 3 to 5 acres if the water 
supply is abundant, the ground not too porous, and 
the lift not more than 20 feet. But if by such an 
arrangement as this a farmer could have only two 
acres or even one acre of cranberries under complete 
control as regards frost and insects, as an adjunct to 
his general farming, it would net him a handsome 
profit which would supplement in an important way 
his yearly income. 

It would, of course, be necessary to be able to 
drain the area quickly after flooding, and if facilities 
are not the best for this, it would be possible to so 
arrange the pump that the water could be thrown 
back into the reservoir again, and this could readily 
be done for small areas where an engine was used 
instead of a windmill for power. 

IRRIGATION OF RICE FIELDS 

In the irrigation of rice fields, where this is to 
be done under the best conditions and where the 
highest quality of rice is to be produced, it is a 
matter of prime importance that the fields shall be 
properly laid out, and that an abundant supply of 
suitable water shall be under complete control. It 
has been pointed out, in discussing the duty of water 
in rice culture, that available statistics make the 



Bice Irrigation 369 

average amount used equal to a flooding of the field 
6 inches in depth once every 10 daj^s, and since so 
much water must be used on this crop, the means 
for handling it must be constructed with ample pro- 
portions. 

In South Carolina, at the mouths of the Santee 
river, where the natural conditions for rice culture 
exist in almost ideal perfection, the fields have been 
laid off into flooding basins, varjdng in size from 
a few acres to thirty and more. Each basin is sur- 
rounded by a dyke, at the foot of which is a main 
distributing ditch 4 to 6 feet wide and 30 to 36 
inches deep, much as has been described for cran- 
berry irrigation, but on a larger scale, and the 
resemblance is made still closer by the division of 
the fields into narrow lands 20 feet in width by 
parallel ditches 36 inches wide and 36 inches deep, 
which are at once the ultimate distributaries and 
the drainage channels. Trunks or sluices are pro- 
vided controlled by semi-automatic tide gates, which 
may be raised at will, on the sea side, to admit 
the water to these ditches and flood the fields to 
any desired depth, and then closed and the water 
retained ; or the gate on the field side may be raised 
and the water withdrawn. 

After the fields have been plowed and seeded in 
the spring, they are flooded to -a depth of 6 inches 
and allowed to so remain until the seed has germi- 
nated and the first three roots formed. At this 
stage the water is let off for three days to force 
rooting, when flooding again occurs to overtop the 



■ 



370 Irrigation and Drainage 

plants and be sure to submerge the highest points 
in the field and start the rice there. This done, 
the water is drawn to a gauge and changed every 
seven daj^s until the stage for dr}' growth has 
arrived, after 21 days, or the fifth irrigation. 

The water is now held oif during 30 days and 
the fields are given two dry hoeings. This stirring of 
the surface of the rice fields appears to have two 
important objects to secure: (1) to destroj' weeds, 
and (2) to so aerate the soil as to admit air to 
the roots and to the niter germs for the develop- 
ment of nitrates. If the soil is not stirred, the 
plants take on a yellow color, which quickly changes 
to a dark green after the cultivation, proving this 
tillage very important. During this time the drj^- 
growth roots are formed, which penetrate the soil 
sufficiently to enable the plants to stand securel\% 
while at the same time they absorb the nitrates, 
potash, phosphoric acid and other ash ingredients 
required to mature the grain. 

The cultivation is made more urgent on these 
fields because of the fine silt borne in the river 
water, which settles and overspreads the surface, 
forming so impervious a film that air can only pass 
it slowly, and if not broken would set up the pro- 
cesses of denitrification, which in turn must check 
the growth of the crop and cause it to turn yelloAV. 

After the dry -growth stage has been passed and 
the head is ready to form, the 7 -day irrigations are 
resumed and maintained until the crop has been 
matured. The frequent irrigations are necessitated 



Rice Irrigation 371 

because of the tendency of the waters to become 
stagnant and poisonous to the rice. So important is 
the complete removal of the stagnant water that pro- 
vision is made at the farther corner of each field, by 
means of a trunk in the dyke, to permit the water 
which has been left standing in the ditches after 
draining to be forced out by the incoming water into 
another ditch leading to a canal or creek, and careful 
watch is kept until the yellow river water has finally 
reached the extreme corner and forced out all of the 
standing water which has been " bagged " in the 
ditches. 

When the rice crop reaches maturity and is ready 
to harvest, a few of the topmost kernels are more 
advanced than the balance of the head and certain to 
shell and fall upon the field. These tip kernels, too, 
are liable to be red, and if allowed to germinate the 
next season would mature heads with kernels still 
more highly colored, and tend in a short time to 
develop the " red rice " which so seriously lowers the 
grade and market price. 

To avoid the development of red rice on the 
marshes, it is the practice, after the harvest has been 
removed, to again flood the fields and germinate at 
once all of the shelled rice which has fallen upon the 
ground, so that the winter frosts shall kill the plants 
and thus remove the red rice. It is stated that if the 
seed is placed in the ground where it cannot ger- 
minate, it may retain its vitality for five years, and 
hence where the practice of fall flooding cannot be 
resorted to it becomes necessary to adopt some system 



372 



Irrigation and Drainage 



of rotation in rice culture which shall furnish oppor- 
tunity for all of the red rice to have been germinated 
and killed before another crop is placed upon the 
ground, and it is the great ease with which the Caro- 
lina planters are able to control this difficulty, and 
the greater cost of rotation necessitated by othe- 




Fig. 101. Plan of rice irrigation, as practiced in South Carolina. 

conditions, which gives them one of their great 
advantages over other rice -growers, enabling them to 
command the highest price in the markets of th 
world. flt 

The detailed method of handling water on a Caro- 
lina rice plantation is represented in Fig. 101, w^here 
eight of the many fields shown in Fig. 67 are 
represented enlarged. 



Bice Irrigation 373 

When the tide falls, the gates on the inner ends of 
the trunks automatically close and prevent the escape 
of the water during any desired period, while the 
dropping of the outer gates prevents the entrance of 
an}' more water until they are again raised. To drain 
the fields with an outgoing tide, it is only necessary 
to lift the inner gates and the work goes forward to 
completion without further attention, so that the 
handling of the water both ways is extremely simple, 
effective, and remarkably cheap. 

The irrigation of rice on higher lands more nearly 
resembles the irrigation of meadows where flooding in 
checks is resorted to, except that here the checks are 
filled to a standard gauge with water, and then a slow 
stream is kept moving into and out of them as long 
as desired, the water usuall}' entering at one corner 
and leaving at the diagonally opposite corner. The 
dividing ridges which form the checks have a height 
of about two feet, and the rice fields are kept under 
water until the heads are formed, when the water is 
drawn off and let on again at short intervals until the 
kernels are well formed, when the water is removed 
and the fields allowed to become dry and the grain 
mature, preparatory to harvesting. 

ORCHARD IRRIGATION 

In orchard irrigation, several methods of distribut- 
ing water are practiced, but there is none followed 
so generally and with so good results as the furrow 
method, represented in Fig. 102, where the water is 



Orchard Irrigation 



375 



being led through an orange orchard in an ideal 
manner, both as to number and size of furrows and 
volume of water which each is permitted to carry. 
The aim is to allow small streams to flow slowly 
through the narrow furrows for a long time, until the 
water has penetrated by percolation deeply beneath the 
surface and at the same time has spread broadly by 




Fig. 103. Orchard irrigation, with wooden flnme in foreground. 



capillarity side wise under the surface mulch. In Fig. 
103 is shown a wooden flume box, w^iich brings the 
water to the orchard, delivering it to the several 
furrows through holes in the side which are %-inch 
to 1 inch in diameter, and which are provided with 
wooden buttons or metal slides for regulating the 
amount of water admitted to each furrow. 

The appearance of the furrows after the capillary 
spread has been considerable is represented in Fig. 




Fig. 104. Capillary spreudi.ig c,f water throngh soil from wat.-r f-.rrows 
1.1 peach orchard, Grand .limction, Colorado. 




Pig. 105. Foot ditch for one orchard and head ditch for low 



Orcliard Irrigation 



371 



104. When the stage of surface wetting shown by 
the dark margins of the furrows has been reached, 
the water has usually percolated to a depth of three 




Fig. 106. Lower orchard taking water from foot 
ditch of Fig. 105. 

or more feet, and has at the same time spread later- 
ally so as to meet beneath the furrows. 

Orchards are frequently arranged as represented in 



878 



Irrigation and Drainage 




Fig. 107. Head ditch or cement Hume for ox'ange orcliard, 
Redlands, California. 

Figs. 105 and 106, so that tlie surplus water from the 
furrows in the upper one is collected in a foot ditch 
shown in the center of Fig. 105, and redistributed in 
a second set of furrows crossing a lower level, shown 
in Fig. 106. The water may be controlled by a simple 
gate in a sluice-box, shown at 1, 1 in Figs. 105 and 



Orchard Irrigation 



379 



106, whicli permits as much water to pass from the 
foot ditch into the lower furrows as is desired. This 
method of irrigation is always less economical of 
water than where the water admitted to each furrow 




Fig. 108. Large young orchard on gravelly flood plain of 
Santa Ana river, with cement flnme. 

is so nicely adjusted that there is no waste into a 
foot ditch. So, too, is there less waste land. 

Still another method of utilizing the water which 
may waste at the foot of the orchard is to have there 
a strip of alfalfa, clover or grass to take this surplus 
with little or no attention or waste. 



380 



Irrigation and Drainage 



But whefre cement or wooden distributing flumes, 
such as are shown in Figs. 107 and 108, are used, 
it is usually quite easy to so completely control the 
discharge that no waste need occur, and in cases 
where water is scanty and expensive this method is 
adopted to great advantage. 




Fig. 109. Model of orchard irrigation by ring furrows. 

When the trees of an orchard are young, it is 
quite unnecessary to irrigate the whole ground, and 
a common practice is to make a furrow around each 
tree, as represented in Fig. 109, allowing the water 
to flow along the single distributing furrow, sending 
it into the side rings for 12 or 24 hours until a cone 
of saturated soil is secured below each tree. As the 



Cultivation After Irrigation 381 

trees become older, the encircling furrows may be 
made larger, until finally it is better to lead the water 
along two single furrows on each side of the row, 
as shown in Figs. 104 and 106. With increasing 
spread of root, the number of furrows would be 
increased until a watering of the whole ground has 
become needful. 



CULTIVATION AFTER IRRIGATION 

A cardinal principle in orchard irrigation should 
ever be thorough, deep saturation, followed, as soon 
as the soil will permit, with thorough cultivation, fre- 
quently repeated. In Fig. 110 is represented an excel- 
lent mulch- producing tool for orchard work. It is 
drawn by three horses ; can be set to run at any 
depth ; makes a clean cut of the whole soil without 
bringing the moist portion to the surface, and is 
provided with a steering wheel, which permits the 
driver to easily throw one end of the long cutting 
blade quickly and accurately to one side and bring it 
close to the trunk of a tree without driving the team 
near enough to endanger either the trunk or limbs. 
As the blade of the tool is 8 feet long, the orchard 
may be covered quickly with it. Smaller sizes, with 
5 -foot blades, are also on the market in California. 

Another form of orchard cultivator to which fur- 
row plows may be attached is represented in Fig. 111. 
Ordinary forms of cultivators must necessarily tend 
more to invert the soil and bring the wet portions to 
the air, and thus be less economical of moisture. They 




Fig. 110. Three-horse orchard cultivator used at San Jose, California. 




Fig. 111. Combined orchard cultivator and furrowing tool. 



Cultivation After Jrrigatiofi 383 

have, however, advantages over the other form for 
going over the ground the first time after irrigation, 
when it is important to break the moist soil into a 
crumbled condition. 

Systems of flooding are also adopted in orchard 
irrigation, sometimes flooding the whole ground or 
small checks surrounding the trees, when these are 
young and the water scanty, but this method is far 
more wasteful of water and much more injurious to 
the texture of the soil, unless it is sandy. When 
following it, care must be taken to prevent water from 
coming against the trunks of the trees and stand- 
ing there. 

In humid climates, on lands where the soil will 
not wash badly, the methods of orchard cultivation 
practiced in the west would give far better results 
than leaving them so persistently in grass, as is the 
more common practice. The moisture of the soil 
should be saved for the trees as a rule, rather than 
used for any other crop after the trees become large. 

SMALL -FRUIT IRRIGATION 

In the irrigation of strawberries, raspberries, black- 
berries, and similar fruits, the furrow method will 
almost always be practiced, leading a slender stream 
along each side of the row and quite close to it. 

Blackberry and raspberry roots penetrate to a suf- 
ficient depth to permit a thorough saturation of the 
soil and good cultivation before the berries are ready 
to pick, so that no irrigation will be required during 



384 Irrigation and Drainage 

the picking. Strawberries, however, are so shallow- 
rooted that water enough cannot be placed within 
reach of the plants to make irrigation during the 
picking season unnecessary. It is, therefore, a com- 
mon practice to lay out strawberry fields in such a 
way that the water may be led only between alternate 
matted rows in deep broad furrows, holding the water 
well up the sides so that it may better spread laterally 
under the plants. This practice, although not as 
economical of water as irrigating between every row, 
has the advantage of not seriously interfering with 
picking, there being always sufficiently firm ground 
upon which to walk. 

GARDEN IRRIGATION 

Garden vegetables are oftenest raised in beds and 
patches of such small dimensions, and on soils so 
light and open, that the irrigation of them is accom- 
plished most readily by methods closely allied to those 
of flooding. A relatively large volume of water is 
quickly brought to the point needed and applied all 
at once, and without waiting for either percolation or 
capillary spreading to take place. 

A method represented in Fig. 112 consists in lay- 
ing the ground off into beds, and getting the seed 
planted, when the surface is overspread with a thin 
dressing of rather coarse litter or horse manure. 

Water is turned into the head ditch, which is 
choked with a little soil or an irrigator's broad 
hoe set so as to turn the stream between the 



Garden Irrigation 



385 



Fig. 112. Diagram of garden beds. 



beds, when the irrigator dams the current at his feet 

with a gunny sack and with a long -handled basin 

dextrously bales the water out as rapidly as it reaches 

him, dashing it over 

the littered surface 

until, in his judgment, 

water enough has been 

applied. The dam is 

then moved and a 

second area irrigated, 

the operation being 

repeated until the 

ends of the beds have 

been reached, when the head ditch is opened and 

closed in another place, turning the water in between 

other beds. 

When the water has had time to penetrate the 
soil, when the surface is beyond danger of crusting, 
and the delicate plants have begun to emerge from 
the ground, the litter may be raked off. In this 
manner a man was observed to irrigate an area 33 
feet by 150 feet in one hour, using the water which 
could flow through a short 3-inch pipe, filling it half 
full, and Fig. 112 is a diagram of the beds, 15 feet 
wide between the waterways. 

Another type of irrigation is shown in Fig. 113, 
where the garden is ridged and furrowed every 18 
inches. Celery is planted on one side of each ridge 
and lettuce on the other. When irrigation is required 
the furrows, 6 inches deep, are flooded one at a time 
from a stream led along their head, and these, when 



386 



Irrigatwn and Drainage 




f"'ig. 113. Furrow Hooding in garden. 

quicklj^ filled, are supposed to hold sufficient water 
for one irrigation, enough to cover the whole ground 
2.5 to 3 inches. In Fig. 114 is represented a cross 
section of the rows. 

In still other cases shallow basins are formed 
about each row of plants, as represented in Fig. 115, 
where cabbages have been set. It will be noted that 
the basins are not only narrow but short, so that 

each may be quickly filled, 
one after another, from a 
f;..v.;-i..,,v.....v^..-....^.....-,,-.vf;v-/,^,;:>^i- ,. gf^ream led along an alley 

Fig. 114. Diagram of section of rows betWCCn twO SCtS. As the 
and furrows in Fig. 113. ^ a i i i i 

plants become larger the 
ridges are gradually cut down to hill the plants, and 
thus form water furrows in their stead. This is one 




Garden Irrigation 



387 



method, as practiced by the Italian gardeners, both 
in their native country and on tlie sandy lands at 
Ocean View, south of San Francisco. 

In Fig. 116 is shown another cabbage field recently 
transplanted by the Chinese gardeners at San Ber- 
nardino, Cal. In this case the field is quickly and 
roughly -ridged and then the large plants hastily set 
low down in one side of the ridge. After irrigation, 
and when the water has settled away so as to permit 
working, a little soil from the ridge is pulled about 
the plants, as seen in the cut. In time the whole 
ridge has been pulled over, leaving the plants stand- 
ing in the center of the crest. 

The French about Paris throw their fields into 
broad double ridges, wide enough to carry two rows 




Fig. 115, Basin flooding of cabbage in garden of sandy soil. 



388 



Irrigation and Drainage 



of vegetables 24 inehes apart, and these are sepa- 
rated by furrows a foot wide and 6 inches deep, 
through which Avater is led for irrigation, and Fig. 
117 is a plan of a section of the upper end of a cab- 
bage field as laid out on the valley sands of the river 
Seine, just outside the city walls. 




Fig. 116. Chinese method of irrigating cabbage, 
San Bernardino, California. 

Melons and cucumbers are planted upon still 
broader beds, 6 to 8 feet wide, separated by water 
furrows, as represented in Fig. 118, the hills being 
planted near each margin of the bed and the vines 
trained awaj' from the furrows. 

At Rocky Ford, Colorado, where melons are raised 



Garden Irrigation 



389 



on a large scale, fields are furrowed every 6 feet 
with a double shovel plow. The seeds are plauted 
in the edge of the ridge away from the furrows, and 
the soil watered through the furrow only, by lateral 
capillary flow, great care being taken to avoid flood- 
ing the surface. Cultivation follows each irrigation 
after the plants are up until the vines become too 
large, but watering must be kept up about once in 
ten days until the crop is mature. 




Fig. 117. Diagram of cabbage irrigation at Gennevilliers, near Paris. 



Another system of irrigating gardens is repre- 
sented in Fig. 119, where the rows are hilled, leav- 
ing shallow furrows between them, but arranged so 
that a stream of water can be led across the ends 
and turned into them one by one. The water is led 
to the lower rows down the middle furrow, and with 
a broad irrigating hoe, having a blade 12 inches 



390 



Irrigation and Drainage 




|Fig. 118. Irrigation of melons and encumbers by Chinese at San Bernardino. 



long and 10 inches deep, the soil at 1 is quickly 
turned over to 2, to form a dam in the stream, 
thus allowing the water to flow between the two 
lower rows until that furrow has been filled to a 
sufficient height. The soil from 3 is then turned 
over to 1, thus closing 1 and allowing the water to 
enter 3. When 3 is full the soil from 4 is brought 
back to 5, which turns the stream in there. When 
4 has received enough, the water is turned into 6 
by moving the soil from there to 4. In this manner 
the irrigator advances from row to row until both 
sides of the whole bed have been watered. 

In other cases, small or large areas of garden 
plants are enclosed in small, shallow basins by throw- 



Oar den Irrigation 



891 



ing up minute dyke -like ridges not more than 6 
inches wide and 4 high. These basins may be 
arranged in a single or double chain, and the water 
led down one side or between them. In this case, 
again, the watering would usually begin at the lower 
end, and with the hoe a section of the border of a 
basin would be drawn out to act as a dam across 
the stream, as shown in Fig. 120. The soil from 1 




rig. 119. Plan of furrow garden flooding by successive rows. 

and 2 would be drawn around to 3, thus turning 
the water into both beds. When these were watered, 
the soil from 4 and 5 would be drawn around to 
6, and the next two beds irrigated. In this manner 
the gardener advances rapidly from bed to bed with 
but little trouble and labor. 



THE IRRIGATION OF LAWNS AND PARKS 

It should ever be kept in mind, where shrubbery, 
trees and grass are grown together, as is so com- 



392 



Irrigation and Drainage 



monly the practice in humid climates, that two crops 
are being grown at the same time upon the land, and 
that under these conditions more water is demanded. 
The roots of shrubs and trees are more deeply placed 
in the subsoil than are most of those which feed the 
lawn grass, and hence all rains too light to over- 
saturate the surface 6 inches are practically secured 
by the grass, and since to maintain a good lawn 




Fig. 120. Plan of basin flooding in garden irrigation. 



requires more water than ordinarily falls as rain, 
even in quite humid climates, it follows that in all 
public parks, cemeteries and ornamental grounds about 
homes, there should be provided an abundant supply 
of water for thorough irrigation. 

In watering lawns and parks, so much water is 
demanded that it ought usually to be applied by 
some flooding system rather than by spraying, as 



Lawn and Park Irrigation 393 

is so commonly the practice. The truth of this 
statement will be readily appreciated when it is 
observed that in order to saturate good lawns suffi- 
ciently to force any water down where it will become 
available to the roots of trees and shrubbery, the 
ground must receive not less than 2 to 3 inches in 
depth of water. But to apply this amount with 
spraying nozzles is impracticable. 

If public parks and cemeteries were more gen- 
erally laid out with a view to thorough irrigation 
as a part of their proper care all through the cen- 
tral and eastern United States, not only would the 
growth of shrubbery and trees be far more luxuriant 
and satisfactory, but dry seasons would not destroy 
the many beautiful trees which so often succumb to 
drought just in their prime. 

Wherever a good well can be had with abundance 
of water and a lift not to exceed 50 feet, a lawn of 
half an acre, with its shrubbery, together with a 
vegetable garden or fruit orchard of several acres, 
may easily be irrigated with a plant not costing 
more than $300 to $500. Such a plant is repre- 
sented in Figs. 121 and 122. This, including well- 
house, 2% horse -power gasoline engine and double- 
acting pump, having a capacity of 80 gallons per 
minute, with over 1,000 feet of 2 -inch distributing 
pipe and hose, cost, when put in place ready for 
work, $440. 

In the portion of this plant shown in Fig. 122, 
part of the 2 -inch iron distributing pipe for the 
lawn and garden, as represented at B, C and D, 



394 



Irrigation and Drainage 



are tapped every 3 feet for short half -inch nipples 
with caps. With this arrangement it is easy to 
take ont water at any desired place, pressure being 




i 



Fig. 121. Small gasoline pumping plant for garden and lawn irrigation. 

maintained in the whole system of pipes when the 
pamp is at work. The pipes for watering the lawn 
are sunk just flush with the sod, and the nipples 
rise obliquely upward so short a distance as not to 
interfere with the lawn mower. The arrows show 
both the slope of the lawn and the waj^ the water 
is distributed. By opening only 7 to 10 nipples at 
a time, a large volume of water is secured, which 
spreads readily over the surface. In the garden irri- 
gation, 15 or 20 rows may be watered at once, and if 



Lawn and Park Irrigation 



395 



a particular stream is a little too strong, this may 
be regulated by thrusting a bit of stick into the 
nipple. For watering beds about the house, four of 




Fig. 122. Plan of lawn and garden irrigation. 

the nipples are made for attaching a garden hose, 
which may also be used to wash windows or a car- 
riage. Altogether, this arrangement is very simple 
and satisfactory for a suburban or country home, 



396 Irrigation mid Drainage 

and would answer admirably for a small market- 
garden, where vegetables and fruits are raised. 

SUB -IRRIGATION 

This method of appljdng water consists in plac- 
ing lines of tile or perforated pipe varying dis- 
tances below the surface of the soil, and distributing 
water through these instead of in furrows or by 
methods of flooding. This sj^stem of irrigation 
quickly suggests itself to most thoughtful men when 
they first begin to handle water for irrigation, on 
account of the many difficulties and inconveniences 
which are associated with surface watering ; but there 
are several very fundamental objections to it which 
have usually led to its abandonment sooner or later 
in nearly every place where tried. 

Were it not for the objections just referred to, 
sub -irrigation would constitute an ideal method of 
applying water, and would be universallj' practiced. 
Could it be used, much of the expense of fitting 
the surface would be avoided ; the fields would be 
almost wholly unobstructed ; all of the ultimate dis- 
tributaries would become permanent improvements ; 
the surface of the soil could not become puddled ; 
mulches developed would not be periodically destroyed, 
and the duty of water would be vastly increased. 
Indeed, so many things appear to be in favor of the 
method that it is only with great reluctance that it is 
abandoned. 

The most insuperable difficulty with sub -irrigation 



Siih - Irrigation 397 

is that of applying sufficient water to thoroughly wet 
the surface, and yet those who have not tried the 
plan feel confident that there will be a great saving 
in this direction ; but the rate of capillary movement 
of water in soil is relatively so slow, and percolation 
so rapid in most cases, that it becomes nearly imper- 
ative that water shall be placed upon the surface, 
where it is most needed and is of greatest service. 

It has been shown under furrow irrigation, where 
the water is applied at the surface, that the streams 
must usually be led as close as every four feet, to wet 
the whole ground, and from this it follows that lines 
of tile laid even closer than this would be required 
in sub -irrigation. In Fig. 123 is shown the wetting 
of the surface which occurred by distributing the 
water through 3 -inch tile placed 18 inches below the 
surface, in which hydrostatic pressure was maintained 
sufficient to cause the water to rise one or two inches 
above the top of the ground. In this experiment 
the tile were arranged as represented at D, Fig. 
124, 10 feet apart, and it will be seen that only 
about 3 feet in width above each line of tile has been 
wet, and yet water enough has been applied to cover 
the area more than 6 inches deep. Even at C, Fig. 
124, where the tile are only 5 feet apart, it was 
necessary to apply 19.68 inches of water in depth to 
completely wet the surface, but in this case the sub- 
soil was more open than it was at D. It is plain, 
therefore, that in order to thoroughly wet the sur- 
face of the ground by sub -irrigation, much more 
water will be required than by furrow irrigation, 



398 



Irrigation and Drainage 



as 



close as 4 feet apart and very 



unless the tile are 
near the surface. 

The second great obstacle in appl3nng sub-irriga- 
tion is the expense required to purchase and place the 
necessary lines of tile. In watering strawberries, 




Fig. 123. Difficiilty of wetting surftice soil by sub-irrigation. 



blackberries, raspberries, and other small fruits, one 
line of tile would be required under each row. For 
orchard irrigation, two lines of tile would be needed, 
one on each side of the row when the trees are small, 
and the number would have to be increased as the 
trees reached maturity, until there was at least one 
every 5 feet. For general field crops, the number of 



Suh - Irrigation 



399 



tile could scarcely be less than one line every 5 feet, 
and it would be necessary to place them at least far 
enough below the surface not to be disturbed in 
working the soil in crop rotation. 




124. Plan of fields for sub-irrigation experiments. 



At one cent per foot for 3 -inch drain tile, the, cost 
for pipe alone would be $87.12 per acre where the 
lines are laid 5 feet apart. In addition to this ex- 
pense, there would be the cost of transportation, 
breakage, and laying of tile connecting with the head 



400 Irrigation and Drainage 

ditcli, and maintenance, which, in the aggregate, 
could not be less than $12.88 per acre when done on 
a large scale and under the most favorable conditions, 
or a total cost of $100 per acre, at the very best 
figure which could be hoped for. 

Only in those cases where tile could be placed 
barely below the surface could there be as high a 
duty of water as with furrow irrigation, and hence, 
where water is high and labor cheap, the cost of water 
would decide against sub -irrigation. 

Where a field has been underdrained, as repre- 
sented in Fig. 124, in the lower lefthand corner, it is 
easy to introduce the irrigation water at the upper 
end of the main, as shown at F, and allow it to set 
back through the laterals. By forcing the water in 
the main to rise to the surface of the ground at G, 
H and A before passing on to lower levels, the 
water in all the tile would be placed under pressure 
which would force it to the top of the ground with- 
out waiting for capillarity to bring it there. In 
this manner if the field were underlaid by sand at the 
level of the tile, the whole area may be quickly 
watered, provided the main has capacity sufficient to 
deliver the water to all the laterals as rapidly as 
percolation can take place from them. With the 
outlet of the tile at E closed and water admitted to 
the main at both F and A, the 7,022 feet of tile took 
water at the rate of 48 cubic feet per minute under 
the 5 acres, or at the rate of 5 gallons per 100 run- 
ning feet of tile where these were placed in sand 33 
feet apart. During the irrigation, water was brought 



Sub - Irrigation 401 

to the surface along most of the lines of tile, as 
represented by the dotted area below A. To do this 
work, 5.8 inches of water on the level were required, 
but it is quite certain that half this amount applied 
at the surface in the proper manner would have ren- 
dered as much service. The time required to apply 
the water at the surface would have been about the 
same, but an extra man would have been needed to 
distribute it, and the furrows would have to be made, 
so that there is this labor to be offset by the cost 
of the extra amount of water required for the sub- 
irrigation. 

But it must be kept in mind that had the field 
not been underlaid by sand and the ground water 
surface near the level of the tile, and had the pressure 
not been held up so as to force the water to rise to 
the surface, these results could not have been attained 
with tile placed as far apart as 33 feet. The applica- 
tion of sub -irrigation to tile -drained areas cannot, 
therefore, be regarded as the best method of watering 
in any but special cases. 

It is quite probable that were this system of 
irrigation to be applied to water-meadows to avoid 
surface ditches, or even to orchards and small fruits, 
there might be experienced difficulties arising from 
the tile becoming clogged, either from sediments 
moved by the water or by the growth of roots into 
the lines of tile. 

When the difficulties which have been pointed out 
as standing in the way of sub -irrigation are con- 
sidered, and when it is recalled that nitrification in 



402 Irrigation and Drainage 

most soils can take place only near the surface, when 
roots are better aerated there, and when here alone 
can germination occur, it seems plain that there can 
be little reason to hope much from this method of 
applying water. 



^Bf" 



CHAPTER XI 

SEWAGE IRRIGATION 

The methods of distributing water in sewage irri- 
gation are essentially the same as those already de- 
scribed. The topography of the field to be watered 
and the character of the soil or of the crop, will 
determine which method shall be employed. It re- 
mains here to state, from the agricultural side of the 
subject, under what conditions sewage irrigation may 
be practiced to advantage and what crops are best 
suited to utilize the water. 

OBJECTS SOUGHT IN SEWAGE IRRIGATION 

There are two main objects sought in the use of sewage 
in irrigation. The first and primary one is to oxidize and 
render innocuous the organic matter which it contains. The 
secondary object is to utilize this organic matter, together with 
be water and other fertilizers which it may contain, in the 
^reduction of crops. Reference has already been made to this 
point in connection with the Craigentinny Meadows, where a 
poor soil has been made to yield a gross income of $75 to 
more than $100 per acre per annum for nearly a century. 

The oxidation and denitrification of the organic matter borne 
in the sewage water must be accomplished largely, if not wholly, 
through the agency of fermenting germs, and this being true, 
it is imperative that the methods of treatment shall be favor- 
able to the activity of these forms of life. 

(403) 



404 Irrigation and Drainage 

CLIMATIC CONDITIONS FAVORABLE TO SEWAGE 
IRRIGATION 

Since the fermentive processes which convert organic matter 
either into nitric acid, which is the nitrogen supply for most 
cultivated crops, or into free nitrogen gas can take place rap- 
idly only under temperatures above 50° F., it follows that sewage 
irrigation is best suited to warm climates, where crops may 
be grown the year round, and where the fermentive processes 
will be least cheeked by frosts. In tropical and semi-tropical 
climates, therefore, sewage disposal by surface irrigation may 
best be practiced when other needful conditions are also favor- 
able. 

In cold climates, like those of the northern United States 
and Canada, where the ground is frozen during five months or 
more of each year, it is plain that only about one -half of the 
sewage water can be used in crop production, and that during 
only about one -half of the year can there be much oxidation 
and denitrification of organic matter. Under these conditions, 
therefore, if water is applied to land one -half of it must be 
filtered by the soil without the concurrent purification which 
results from fermentation, and this being true, there can be 
only so much of purification as naturally results from the 
physical filtration and such chemical fixation as the soil may be 
capable of accomplishing. 

It is true that the purification of sewage resulting from 
filtration through soil is very considerable, so that if isolated 
lands of sufficient area are selected for this purpose, the organic 
impurities reaching the ground water will be greatly reduced. 
It is also true that in cold climates fields to which no sewage 
has been applied during the warm season may be reserved 
specially for the reception of it during the winter. These soils 
would, therefore, be comparatively dry and capable of receiving 
6 to 12 inches of water and of retaining it by capillarity 
until warm weather could subject it to organic purification, 
and when crops could also be made to utilize the nitrates 
developed and other fertilizers brought by the water. 



Sewage Purification 405 

To handle the sewage in this manner, it would be needful 
to bring it to the fields in underground conduits, and to have 
the lands laid out for flooding in cheeks of suitable size, sur- 
rounded by barriers of the desired height, but the great diffi- 
culty to be met is the amount of land needful for such a 
system. Allowing 50 gallons of sewage per day per person, 
a city of 30,000 would require 828 acres to receive the sewage 
during 180 days if each check were to be flooded to a depth 
of 12 inches. 



THE PROCESS OF SEWAGE PURIFICATION BY IRRI- 
GATION OR INTERMITTENT FILTRATION 

The extremely careful and extended investigations eon- 
ducted by the State Board of Health at Lawrence, Mass., begun 
in 1888 and still in progress, have shown that the purifying 
of sewage as it passes slowly over the surface of sand grains 
freely exposed to contained air, is the result of bacterial growth, 
and that when these germs are not present the sewage comes 
through the filter as impure as it went in so far as its dangerous 
nitrogen compounds are concerned. But if it is allowed to 
pass through slowly enough in the presence of an abundance 
of air, the water emerges with so nearly all the nitrogen com- 
pounds converted into nitrates that it is as free from them 
as the purest spring water. 

The essential condition is that an inch or two of water 
shall be spread out over the surface of the soil grains in 
enough of the upper soil, where free oxygen may gain access 
to the colonies of niter -forming germs which multiply there 
and feed upon the organic nitrogen in the water, if only 
there is an abundance of free oxygen to meet their other 
needs. When a new quantity of water is added to the soil, 
the purified layer is swept downward by the new supply, 
which at the same time drags in after it a fresh supply of 
air, and thus the work goes on. 

If the sewage water is added too rapidly, before the germs 



406 Irrigation and Drainage 

have completely used up the organic nitrogen, then it will be 
only partly purified ; or if the flow over the field is made con- 
tinuous, then the supply of oxygen in the soil becomes so 
small that the germs are unable to carry forward the work, 
and organic nitrogen passes through largely unchanged and 
liable to become the food in drinking water of other but 
dangerous forms. 

SOILS BEST SUITED TO SEWAGE IRRIGATION 

In humid climates, where the rainfall is both frequent 
and abundant, the lighter loams and sandy soils are best 
suited to this type of irrigation, because upon them there is less 
danger of water-logging. It should be understood, however, 
that from the agricultural standpoint sewage may be applied 
to any soil, provided it is not used in too large quantities or too 
continuously ; but as the sandy soils are usually more in need 
of artificial fertilization, and at the same time likely to be 
deficient in water, they are preeminently suited to this use, and 
will usually be chosen by city authorities when they are avail- 
able, but simply because a smaller number of acres will answer 
the purpose and the cost of the plant be less. 

The agricultural value of sewage when properly applied to 
land has been so thoroughly demonstrated under so many condi- 
tions of soil and climate that there can no longer be any doubt as 
to the desirability of its use if the expense of getting it to the 
land were eliminated, and it would appear that lands enough in 
the vicinity of most cities could profitably receive and use the 
sewage if only it were led to them. 



DESIRABILITY OF WIDER AGRICULTURAL USE OF 
. SEWAGE IN IRRIGATION 

In countries like Italy, where there are extensive canal 
systems largely used for irrigation, it would appear that sewage 
disposal by irriga,tion should become the general practice, pro- 



Agricultural Use of Sewage 



407 



vided the canals are carrying constantly a sufficient volume of 
water to make the needful dilution. The disposal of the sewage 
of the city of Milan in this manner has already been referred to 
as extremely satisfactory from the agricultural point of view. 

In speaking of the opportunities for and the desirability of 
improving sandy lands in various parts of the eastern United 
States and in the South by silting, it was pointed out that many 




Fig. 125. Instruction of practical gardeners in garden irrigation. 

hundreds of square miles of now nearly worthless lands could be 
reclaimed by methods of irrigation, and wherever this shall be 
undertaken the disposal of the sewage of the same sections 
through the canal waters could not fail to be of great advantage 
to the lands when applied either in winter or in summer. 

Outside the walls of the city of Paris, on the once nearly 
worthless gravelly sands of the Seine, is located a garden whose 
sign is represented in Fig. 125, where, in the midst of a district 



408 



Irrigation and Drainage 



devoted to sewage irrigation, an effort is being made to teach in 
a concrete way how thoroughly purified sewage water may be 
made by irrigation, and what luxuriant growths may spring from 
nearly sterile sands. Fig. 126 is a view within the garden, 
where grapes are growing on the left, with dwarf pears and 
apples on the right, while in the center is a trench of water 
cress grown for market in filtered sewage, the trench being at 
the foot of one of the drainage lines leading the filtered water 




Fig. 126. Sewage irrigation, model garden, Paris. 

to the Seine. So clear was this water that it had the sparkling 
brilliancy of that from the purest springs, and outside the 
garden women and children came with their buckets and filled 
them for use at home. Inside, the superintendent keeps a glass, 
and insists that every visitor shall taste and convince himself 
how sweet and pure the water is. Here and further out, at 
Gennevilliers, the lands are laid out and divided much like 
village lots, where homes, with their vegetable, fruit and flower 



Sewage for Garden Irrigation 409 

gardens, are being established, and sewage water was handled 
there in 1895 by small gardeners with great skill and profit. 
The lands are held at $1,000 per acre, and rent at a high price. 
The sewage for irrigation is carried beneath the surface in 
closed pipes, which are provided with a system of hydrants for 
taking out the water where needed, and Fig. 127 shows one of 
these, while Fig. 128 is taken at the same place, standing at 
the hydrant and looking down the open ditch leading the 
water to gardens and orchards, where it is to be used. 
Flowers, garden vegetables and fruits were growing upon these 
grounds in great luxuriance for the city markets. If such 
results as these can be secured in France, why should not the 
philanthropic zeal of Greater New York join with the capital 
of that city and lead a portion of the water of the higher 
lands, together with the sewage of the inland towns and" cities, 
which is now polluting the streams, down upon the flat New 
Jersey sands and convert them into gardens of industry and 
plenty, where the unfortunate mothers, with their children now 
in the dark streets, could be helped to comfortable homes sur- 
rounded by conditions which make physical, intellectual and 
moral growth possible. 

CROPS SUITED TO SEWAGE IRRIGATION 

There is no crop more generally grown on sewage farms 
than grass, which is fed green, as cited in the cities of Leith 
and Edinburgh and at Milan ; as silage, as has been done at 
Croyden and Nottingham, or made into hay, as at Preston. At 
Blackburn and at Croyden, also, the lands are extensively pas- 
tured, at the latter place by coach and draft horses of the city 
for a season, to allow their feet to recover from the jar and 
shock of stone pavements. 

In England and in Italy very heavy crops of grass are 
grown, yielding all the way from 40 to 70 tons per acre per 
season. The grass most extensively grown in Europe is the 
Italian Rye Grass, but it is not permanent, and the land must 
be plowed and reseeded every three or four years if heavy 




Fig. 127. Sewage hydrant at Geniievilliers. 





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i3 


fl 


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ijj^ 


lir ' 




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l^^^^^v. ^ 


} 






^ 


1 




"^^iHj 


■ 


M 


I 


t~- 




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H^'^v'j 


p 


m 


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Fig. 128. Stone distributing canal leading from hydrant in Fig. 127. 



Crops for Sewage Irrigation 411 

yields are desired. On the Craigentinny Meadows, most of the 
grasses are the native forms, wliich soon crowd out the Rye 
Grass if it is not reseeded. 

Both oats and wheat are extensively grown on sewage 
land, but in these eases the land is usually only irrigated dur- 
ing the winter. Potatoes, turnips and mangels, as well as 
cabbage and cauliflower, are also grown. 

At Croyden and Preston, potatoes are grown on a large 
scale on winter irrigated land and the crop sold at auction 
when mature at $60 to $75 per acre, the purchaser digging the 
potatoes. Fig. 129 shows a crop of early potatoes grown at 
Croyden which sold in July for £15 per acre, and Fig. 130 is 
a view of the cement ditch in which the water is brought to 
the fields from the city. When summer irrigation of potatoes 
is practiced at Croyden, the superintendent stated that he pre- 
ferred to use the water only after it had drained from another 
field. He also stated that he thought the sewage water tended 
to intensify the scab. 

At Nottingham, where much wheat is raised, this is grown 
on winter irrigated land, but cabbage, turnips and mangels are 
irrigated in the summer as well as winter. The cabbages 
raised here -are the large stock varieties, planted in rows 4 
feet apart with the plants 3 feet apart in the row, and 
enormous yields are secured of the vegetables named and fed 
to a herd of from 800 to 1,000 cows. 

At Gennevilliers, nearly all varieties of garden truck were 
being raised with great success, and there were orchards of 
pears, prunes and apples, and vineyards of grapes, heavily 
loaded with fruit in August of 1895. So, too, at Berlin, 
mangels, turnips, celery, onions, parsnips, beans, cabbage and 
cauliflower were raised on their sewage farms. 

While the general practice in Europe seems to be to favor 
summer irrigation of grass, and winter irrigation for small 
grains and cultivated crops generally, it appears clear that 
there are few if any crops to which sewage may not be applied 
with great advantage if only rational practice is followed. 

It will be readily understood that where fertilization is the 











>^,^^ :W?^^^- -•-•7^^^•v■ 



rig. 129. Harvesting early potatoes on Croyden sewage farm, England. 




Fig. 130. Cement canal at sewage tarm, Croyden, England. 



Sewage Irrigation and Healthfulness 413 

main object, together with the disposal of the sewage, lands 
may be irrigated at once after the removal of a crop, such as 
wheat or any of the small grains, so that there may be ample 
latitude for distributing the water at almost any season of 
the year. 

In climates where the winters are severe, it is necessary to 
apply the sewage to land not in grass or other perennial crop, 
as the freezing of thick coats of ice over the meadows is quite 
certain to greatly injure if not kill the grass. Another point 
which the agriculturist should keep in mind and guard against, 
is the application of sewage to crops in too concentrated a form, 
and especially should it be so much diluted or strained that the 
sludge will not collect upon the surface in sufficient quantity 
to close up the pores of the soil and interfere with proper 
aeration. 

INFLUENCE OF SEWAGE IRRIGATION UPON 
THE HEALTH 

Reference has been made to experiments and observations 
which show that the feeding of grass from sewage farms to 
milch cows produces no injurious effects upon the milk itself. 
The late Colonel Waring states that the health of the people 
living upon the sewage lands at Gennevilliers is generally excel- 
lent, and that "even in 1882, when there was a cruel epidemic 
of typhoid fever in Paris, there was none here." He further 
says : " If there is still room for doubt on any point, it is as 
to the character of the few bacteria which escape the action of 
the process employed, and are found in the effluent. It is not 
known that disease germs exist among these, and it is altogether 
probable that they do not. So far as these organisms are 
understood, it is thought that they cannot withstand the 
destructive activity of the oxidizing and nitrifying organisms 
which are always present, and it is believed that only these 
hardier organisms exist in the effluent of land -purification works. 
Certain it is that no instance has been reported where con- 
tagion was carried by such effluents, and experience at Genne- 



414 



Irrigation and Drainage 



villiers has shown that typhoid fever and cholera, when rife in 
Paris, were completely arrested at the irrigation fields." 

" In the Massachusetts table of comparison of the purified 
effluent of seven sewage filters and the waters of* seven wells 
used for drinking by many persons, it is shown that there 
were three and one -half times as many bacteria in the well 
waters as in the effluents." 



Part II 
FARM DRAINAGE 



CHAPTER XII 

PRINCIPLES OF DRAINAGE 

It has been pointed out that if all of the irri- 
gated lands of the world were brought together in 
a solid body, they would scarcely aggregate more than 
an area 500 miles on a side, or 250,000 square miles. 
But Professor Shaler estimates that in the United States 
alone, east of the 100th meridian, there are more 
than 100,000 square miles of swamp lands. Some of 
these have been reclaimed by drainage, and the great 
majority of them could be, if the expense of the 
reclamation would be warranted by the returns which 
would follow. In the Canadas, in Europe, and in 
other portions of the world, also, there are vast areas 
of land, when measured in the aggregate, which 
must be drained before they can become agricul- 
turally productive. Hence the principles of land drain- 
age, like those of irrigation, must be clearly under- 
stood by those who are concerning themselves with 

(415) 



416 Irrigation and Drainage 

the great world problems of better homes and all 
which these mean. 

Further than this, on account of the fact that a 
large majority of swamp lands and lands which may 
be improved by drainage are not massed together, but 
are scattered broadly in small tracts, so related to 
the higher and better -drained lands that these must 
often be improved in order to work the others to 
the best advantage, the principles of farm drainage 
become a matter of great importance to a large pro- 
portion of the rural population, and through good 
roads to the people of cities as well. 

THE NECESSITY FOR DRAINAGE 

The first and most fundamental necessity for land 
drainage, as has been pointed out in discussing 
alkali soils, is the removal of the more soluble salts 
formed by the decay of rock and organic matter, 
because too strong a solution of salts in the soil water 
is fatal to the growth of vegetation, and gives rise 
to the alkali lands. So long as there is sufficient 
leaching to hold the soluble salts down to small per- 
centages, so that neither plasmolytic nor toxic effects 
result, then the first imperative demand for thor- 
ough drainage in all soils is met. 

The second imperative demand for drainage is to 
prevent a stagnation of the soil water, which means, 
to avoid the exhaustion of oxygen from the air in 
the soil water and in the spaces not occupied by 
water, because an abundance of free oxygen in the 



Necessity for Drainage 417 

soil is a fundamental necessity to plant life, and 
thorough drainage secures this. 

The third demand for drainage is to render the 
soil sufficiently firm and solid to permit the field or 
road to be moved over without difficulty or incon- 
venience. If the spaces between the soil grains are 
completely filled with water, then there is no surface 
tension, and so only a slight friction to bind the 
grains together, and hence they move so easily upon 
one another as to be unable to sustain much weight, 
and the horse or wagon mires. 

Everyone is familiar with the hard surface pos- 
sessed by wet beach sand, from which the water has 
just withdrawn, and how yielding it is when under 
water and also when it becomes dry. In the first 
case, the sand grains are bound together by the thin 
films of water which surround them ; in the second 
case, there is no free water surface between the grains, 
and the sand tends simply to float and so moves 
easily ; while in the third case, when the sand is 
dry, the binding water films have either drained 
away or have been lost by evaporation, hence there 
is nothing to hold the grains together. 

The hard, firm character of a clay soil when it 
loses its moisture is due to the fact that the grains 
are so small and so close together that the little 
material which is held in solution in the soil water 
cements them together when dry. Were the grains 
large like those of the sands, with few of the fine 
particles between them, the contact areas would be so 
few and so small that little binding could result. 

AA 



418 Irrigation and Drainage 

THE DEMANDS FOR AIR IN THE SOIL 

It must ever be kept in mind that an abundance of 
free oxygen in the soil is as indispensable to the life 
of the plant as it is to that of an animal. The 
germinating seeds must have it, or they rot in the 
soil ; the roots of plants must have it to enable 
them to do their work ; and the vast army of 
soil bacteria, which change the nitrogen of decaying 
organic matter into nitric acid, which is the chief 
nitrogen supply for most higher plants, must have 
it or they cannot thrive. Again, those very impor- 
tant germs which live on the roots of clover and 
other allied plants, and which are the chief source 
of the organic nitrogen of the world, must have an 
ample supply of both free oxj-gen and free nitrogen 
in the soil, or thej^ are unable to accomplish their 
task. 

Again, there lives in all fertile soils a class of 
germs which have the power of breaking down 
nitrates, or even organic matter, to supply them- 
selves with oxygen whenever the conditions are such 
that the soil does not contain enough to meet their 
needs. But when these germs are forced to do this, 
as happens in a water -logged or poorly drained soil, 
the nitrogen of the soil nitrates and of organic 
matter is liberated in the form of free nitrogen 
gas, and hence the soil may thus be depleted of 
this most expensive ingredient of plant -food wherever 
proper drainage does not exist. 

Finally, many purely chemical changes taking 



Drainage Ventilates the Soil 419 

place in the soil, which are essential to its fer- 
tility^ demand both free oxygen and carbon dioxide, 
so that here is another need for good drainage, in 
order that air may enter the ground in abundance. 

HOW DRAINAGE VENTILATES THE SOIL 

Where standing water would be found in holes 
sunk 18 to 24 inches below the surface, capillarity 
would hold the pores of a fine soil so nearly full 
of water to the top of the ground that there would 
be little room left for air to enter ; but when the 
ground water is permanently lowered three or four 
feet, as is done by underdraining, the roots of plants 
penetrate the soil more deeply, and, as they die and 
decay, leave passageways leading to the surface, into 
and out of which the air readily moves. Earth- 
worms, ants, and other burrowing animals penetrate 
the ground more deeply, and open other ventilating 
flues of much larger magnitude than those left by 
the roots of plants, and so greatly increase soil ven- 
tilation as a result of drainage. 

Then, again, when the deeper clays dry out, as 
they will after underdrainage, shrinkage checks form 
in them in great numbers, opening tiny fissures 
through which the air moves more freely with every 
change of temperature and pressure of the atmos- 
phere above. With the deeper and more thorough 
penetration of soil -air, carrying with it the car- 
bonic acid developed near the surface, there begins, 
through the agency of the soil water, a solution of 



420 Irrigation and Drainage 

the lime which in its turn tends to force the fine 
clay particles into larger compound clusters, thus ren- 
dering the soil more open, and hence better drained, 
better ventilated, and at the same time better and 
more thoroughly occupied by the roots of plants. 

But all of these changes, which result directly 
from lowering the ground -water surface, are only 
means which make underdrainage more effective in 
ventilating the soil. In an underdrained field, where 
lines of tile are laid 3 to 4 feet deep and 50 to 100 
feet apart, there is provided a very effective system 
of soil ventilation as well as of drainage ; for with 
every fall of the barometer and rise of soil tempera- 
ture, some of the deeper soil -air expands and drains 
away through the lines of tile. Then, when the 
barometer rises again, or when the soil temperature 
falls, a volume of air equal to that which left the 
soil under the other conditions now enters it again, 
not onlj^ through the surface of the ground, but 
also through the tile drains. It is thus seen that 
a deep, well -laid system of tile drains permits the 
free oxygen of the air to reach the roots of plants 
both from above and below. Under these condi- 
tions, the roots of crops are better supplied with 
oxygen ; nitrates develop faster and deeper in the 
soil ; there is less occasion for denitrification to set 
in, and so larger yields result. 

When deep underdrainage has permitted the roots 
of plants to penetrate the soil from 3 to 4 feet and 
there withdraw moisture, this action on their part 
becomes a means for drawing air into the ground, 



Drainage Ventilates the Soil 421 

both from the surface and through the tile drains, 
because the removal of the soil water by the roots 
leaves an open space, which must be filled with air 
so far as capillarity fails to do it with water, and 
hence deep root feeding means deep soil ventilation. 

Then, again, when heavy rains fall which move 
downward through the soil, they displace both the 
air and the water previously there, crowding them 
forward into the drains, and then draw in after them 
a fresh supply from above. But only on' well- 
drained soils is this action marked and helpful. 

A word should be said here regarding the value 
of clover and alfalfa as soil ventilators, for by their 
thicker, stronger roots they set the soil aside more than 
most other cultivated crops do, and when these roots 
decay the soil is left better aerated and better 
drained. Further than this, the roots of these legu- 
minous plants remove from the soil both free oxygen 
and free nitrogen, and in so far as they do this with- 
out returning an equal volume of another gas, their 
action tends to develop a vacuum which must be 
filled by bringing in a fresh supply from without. 

TOO THOROUGH AERATION OF THE SOIL 

There may be too strong and rapid changes of 
soil-air, just as there may be too rapid and complete 
drainage. If the air enters a rich, damp soil too 
rapidly, there is so strong a development of nitrates 
that the humus and other organic nitrogen are quickly 
changed into the soluble forms, and rapidly leach 



422 Irrigation and Drainage 

away. It is in this manner that coarse, sandy soils 
are impoverished, and their lack of productiveness 
is often due quite as much to too thorough ventilation 
as to too complete drainage ; and in handling these 
soils the utmost care should be exercised to keep 
the content of humus high, the moisture plenty, and 
the winds from drifting away the finest dust particles, 
because all of these tend to close up the pores, giving 
the soil a texture which diminishes the amount of 
ventilation. 

DRAINAGE INCREASES THE AVAILABLE SUPPLY OF 
SOIL MOISTURE FOR CROPS 

When soils are poorly drained during spring and 
early summer, the root system of the various crops 
is forced to develop near the surface, and if this is 
the case until the demands for moisture become large, 
the soil in which the roots are confined becomes very 
dry, because capillarity brings the water up from 
below too slowly to meet the demand. 

It is a familiar fact that a damp cloth is much 
better to remove water from the floor than a dry one, 
and the same is true of soils ; water rises by capil- 
larity in them when quite moist much faster than 
when they become dry, and so it is a matter of the 
greatest moment to keep the surface soil, beneath the 
mulch, as damp as the best conditions for growth 
will permit. When the deeper soil in the spring and 
early summer is well drained, and the roots of the 
crop penetrate it, they not only find themselves closer 



Drainage Increases Available Moisture 423 

to the ground water supply, but not so many roots 
are forced to take the moisture near the surface, and 
hence for this reason capillarity is better able to hold 
the water content up to the saturation needed. 

With the soil near the surface moist, where nitrates 
are mostly formed, a better supply of these is kept 
up, while at the same time there is moisture enough 
to hold them in solution and to enable the roots 
to obtain them. When other roots are deeper in the 
ground, these may chiefly draw water to meet the 
necessary evaporation which goes on in the leaves, 
and thus reserve the surface moisture for developing 
plant -food and giving it to the plant. In this way 
it happens that crops suffer less in times of drought 
on well -drained, heavy soils than they do on the same 
soils not drained. 

SOIL MADE WARMER BY DRAINAGE 

There is no cause so effective in maintaining a low 
temperature of the soil in the spring as the water 
which it contains, and which may be evaporating from 
its surface. One reason for this influence is found 
in the fact that more heat is required to change the 
temperature of a pound of water one degree than the 
same weight of almost any other substance. Thus, 
while 100 units of heat must be used to warm 100 
pounds of water from 32° F. to 33° F., only 19.09 
units are required to raise the temperature of the 
same weight of dry sand, and 22.43 units an equal 
weight of pure clay through the same range of 



424 Irrigation and Drainage 

temperature. Stated in another waj^ the amount of 
sunshine which will warm a given weight of water 
10° F. will raise the temperature of an equal weight 
of dry sand 52.38° F., clay 44.58° and humus 22.6°. 
It is plain, therefore, that very wet soils must warm 
in the sun more slowly because the water which they 
contain tends to hold the temperature dowu. 

The chief cause, however, which makes a wet, 
undrained soil colder than the better drained one, is 
the cooling effect which results from the more rapid 
evaporation of water from the wetter soil surface. 
When the bulb of one of two similar thermometers 
is covered with a jacket of muslin moistened w^ith 
pure water, and the two are swung side by side in 
a dry air, it will often be observed that the bulb bear- 
ing the moist cloth will have its temperature lowered 
as much as 20° F. by the cooling effect of evaporating 
water. So, too, when water evaporates from any sur- 
face, no matter what, its temperature is lowered in 
proportion to the rate at which evaporation is taking 
place. The teakettle boiling over the hot fire has 
its temperature constantly held down to 212° by the 
rapid evaporation of water, although the heat of the 
fire playing upon it is very many degrees hotter. 

It is the same way with a wet soil through which 
water is continually brought to the surface as rapidly 
as it can be evaporated in the heat of the sunshine. 
The loss of the water in this way necessarily holds 
the temperature down, and the lower the more rapidly 
the evaporation takes place. The following table* 

*Tlie Soil, p. 227. 



soil 


soil 


ence 


66.5° 


54.00° 


12.50° 


70.0° 


58.00° 


12.00° 


50.0° 


44.00° 


6.00° 


55.0° 


50.75° 


4.25° 


47.0° 


44.50° 


2.50° 



Importance of Soil Warmth 425 - 

shows the observed difference in temperature of a 
drained and an undrained soil : 

Temperature 
Condition of Temp, of of drained of undrained Differ- 
Date Time weather air 

A^^ji OA 3.30 to Cloudy, with brisk „„ f;o w 
^P^^^24 4p^ east wind ^^'^ ^• 

AT>ril9'^ ^ *^ Cloudy, with brisk (-AnOF 
April 25 3 30 ^ ^^ ^^^^ ^^^^ 64.0 J^ . 

Ar^T-n 9R 1.30 to Cloudy, rain all the 4= no w 
April ^b 2 p. m. forenoon ^^'^ * • 

A T^v^i 07 1-30 to Cloudy and sunshine, ^q no t? 
April 27 2 p. m. wind S. W. brisk ^^'^ ^• 

Atxt^i 98 "7 to Cloudy and sunshine, .^ no p 

The difference in the rate of evaporation from 
clayey soil and sandy soil, when both are well 
drained, will often be enough to leave the clay 
soil 7° F. colder in the surface foot and 5° colder 
in the second and third feet below the surface. 



IMPORTANCE OF SOIL WARMTH 

Ebermayer concluded from his observations that 
relatively little growth can take place with most cul- 
tivated crops until after the soil temperature has 
been carried above 45° to 48° F., and the maximum 
results are reached only after a temperature of 68° 
to 70° has been attained. 

Sachs showed that both pumpkin and tobacco 
plants wilted, even at night and with an abundance 
of moisture in the soil, when its temperature fell 
much below 55° F., the osmotic pressure being then 
too feeble to maintain a sufficient movement of soil 
moisture to keep the plant cells turgid. Phenomena 



426 



Irrigation and Drainage 



similar to this are often observed early in the spring, 
when leaves are just unfolding. A strong drying 
wind on a cool day, with the soil also cold, withers 
the leaves much as if they had been frosted. 

The germination of seed is very much influenced 
by the temperature of the soil, maize requiring 16 
days to appear above the ground when the soil tem- 
perature is 60° F., or below, when if the warmth is 
72° or above, 3 days or less will do the same work, 
besides giving much stronger plants. These effects 




Kg. 131. Intluenee of soil temperature on the rate of germinatiou of maize. 



of soil temperature are clearly demonstrated in Fig. 
131. Indeed, it will often happen that when seed 
of rather low vitality is planted in a soil a little too 
cold, germination will not take place at all, or if it 



Importance of Soil Warmth 427 

does, the plants are so much enfeebled that only a 
slow growth results afterward. 

In the early part of the season, when ground is 
being fitted for seeding, it should ever be kept in 
mind that one of the chief objects of the early and 
thorough tillage is to develop an abundance of 
nitrates in the soil for the use of the crop. But 
this is done by making the soil warmer, and by 
introducing an abundance of air into it when there 
is a good supply of moisture associated with the 
humus upon which the niter germs feed. Thjse 
germs cease to develop niter from humus when the 
soil temperature drops to 41° F. ; the action is only 
barely appreciable at 54° F., and it reaches its maxi- 
mum rate only at a temperature of 98° F. 

Now, the early, deep stirring of the soil in the 
spring prevents the moisture from coming up from 
below, and so lessens the rate of evaporation ; this 
allows the soil to become warmer. Besides the heat is 
not conducted as rapidly downward when the soil is 
loose ; this makes the stirred, well ventilated portion 
warmer also, so that for the germination of the seed 
and for the development of plant -food, deep early 
tillage is very important. It is plain, also, that the 
well -drained field not only can be tilled earlier and 
deeper, but will also have the soil warmer and richer, 
for the reasons just stated. 

For the same reason that sugar dissolves faster in 
warm than in cold water, so the ash ingredients of 
plant -food are dissolved faster, and stronger solutions 
of them are formed in the warm than in the cold 



428 Irrigation and Drainage 

soils, and hence land drainage may be beneficial to 
crop growth in this manner. 

CONDITIONS UNDER WHICH LAND DRAINAGE 
BECOMES DESIRABLE 

It must be kept ever in mind that all lands, of 
whatever kind, require draining, but it is extremely 
fortunate that for most lands this is done by the 
natural methods of percolation and underflow of 
ground water. 

The cases in which it becomes desirable to supple- 
ment the methods of natural drainage fall into five 
classes : first, those comparatively flat lands or basins 
upon which the surface waters from surrounding 
higher land frequently collect ; second, areas border- 
ing higher lands, whose structure is such as to permit 
the underflow of the ground water from the adjacent 
regions to rise from beneath, thus keeping the soil 
too wet ; third, lands regularly inundated by the rise 
of the tides, or which would be if not shut off by 
dykes ; fourth, those extremely flat lands which are 
underlaid by considerable thicknesses of close, heavy 
beds of clay, through which water does not readily 
percolate, and which lie very close to the surface, so 
that the clays become the subsoil of the fields, and 
fifth, lands like rice -fields, water-meadows and cran- 
berry marshes, to which water is applied by irrigation 
in excessive quantities. It may also be found desir- 
able on some irrigated lands to introduce drainage to 
remove injurious salts, as described under alkalies. 



Origin of Ground Water 429 

THE ORIGIN OF GROUND WATER AND ITS 
RELATION TO THE SURFACE 

To understand the laws governing the flow of 
water into tile drains and ditches, it is necessary to 
know how the flow into streams and lakes takes 
place, and how the surface of the water in the 
ground is related to that in the streams and lakes 
into which it is continually draining. 

The rains which fall upon the surface tend, first 
of all, to sink vertically downward until they reach 
the level at which the pores in the soil or rock are 
completely filled with water. There are no soils and 
very few rocks through' which there can be abso- 
lutely no flow, but the downward percolation is very 
much slower in some than it is in others. This 
being true, everywhere beneath the land surface a 
place may be reached where the pores are filled with 
water, and the level at which this occurs is called 
the ground -water surface. 

This ground -water surface is seldom horizontal, 
but usually rises and falls much as does that of the 
ground above it, but with gradients less steep. In 
Fig. 132 is represented a section of land adjoining a 
lake, where the differences in level of the surface are 
shown by means of contour lines passing through all 
places, having the height above the lake indicated by 
the number set in the line ; while in Fig. 133 the 
surface of the ground water for the same area is 
also indicated in like manner. The data for the levels 
of the ground water were procured by sinking wells 



r5=»- 




Fig. 132. Contours of the surface of the ground in the vicinity of a 
tile-dr9.ined area, 




Fig. 133. Contours of the level of the ground- water surface under the 
locality represented in Fig. 132. 



432 



Irrigation and Drainage 



at the places designated by the small numbered cir- 
cles. 

Referring to the two figures, it will be observed 
that there is a marked tendency for the ground- 
water surface to stand highest where the level of the 
field is also highest, and that there are valleys in the 
ground -water surface beneath the valleys in the field. 
It will be seen that the water rises as the distance 
from the lake increases, and that in places it stands 
10 and even 20 feet higher. 

This distorted surface of the ground water cannot 
be a condition of rest, for gravity tends continually to 
force a flow from the higher toward the lower levels 
along the lines indicated by the arrows shown in Fig. 
133. Since the further this water must, travel through 
the soil to reach the lake the more resistance it must 
meet, it is plain that a greater pressure will be re- 




Fig. 134. Diagram of lines of flow of water in the drainage of a river valley, 

quired to overcome this resistance, and hence the 
water must stand higher in the ground the farther the 
distance to the drainage outlet. The space enclosed 
by the rectangle in Fig. 133 is an area which required 
underdraining to fit it for farm crops, and the reason 
it did is clearly shown by the contours of the two 



Movements of Ground Water 433 

maps and by the arrows representing the lines of 
underflow, which concentrate from the surrounding 
higher lands to pass beneath this section so near 
the surface that the strength of capillarity was suffi- 
cient to over -saturate the soil above. The influence 
of the tile drains in lowering the surface of the 
ground water is plainly shown by the distance the 
contours are carried back from the lake shore, as seen 
along the line marked "tile drain." 

In the case of streams winding through valleys, 
the water comes to them at every point along their 
course by slow seepage, entering the channel through 
the banks and bottom in the manner represented in 
the diagram, Fig. 134, where the heavily shaded por- 
tion represents the soil filled with water and the lines 
with arrow points the direction of flow. 

In Fig. 135 is represented the surface of the 
ground water in the valley of the Los Angeles river, 
California. The data for the contours were procured 
by sinking wells at the points designated by the 
heavy dots. From the map it is clear that the water 
stands higher and higher above the bed of the stream 
as the distance back increases, and that there must 
be a steady flow down the valley and toward the 
river, thus draining the surrounding country. Indeed, 
in a distance of about 11 miles the measured growth 
of the Los Angeles river in 1898 was 60 cubic feet of 
water per second, and yet no visible streams entered, 
the supply coming by slow seepage along the banks 
and bottom of the entire length of the section 
measured. 

BB 



Ground Water Gradient 435 

It will be clear, therefore, from the cases cited, 
that wherever the moving sheet of ground water ap- 
proaches within capillary range of the surface of the 
ground, there the soil is liable to be too wet for crops 
unless underdrained. 

RATE AT WHICH THE GROUND -WATER SURFACE 
RISES AWAY FROM THE DRAINAGE OUTLET 

In well 29 of Fig. 133, situated 150 feet from the 
lake, the water stood 7.214 feet above the level of the 
lake June 27, 1892, thus showing a rise of 1 foot in 
every 24.4 feet. At another place in the same locality, 
but not shown in the map, a well 1,250 feet from the 
lake shows the ground -water surface to stand 52 feet 
above, thus giving a gradient of 1 foot in 24 feet. 
Later in the season, when the ground had become 
dryer, the gradient at well 29 became 1 foot in 
35.86 feet. 

Between tile drains 33 feet apart and 4 feet deep, 
laid within the rectangle of Fig. 133, measurement 
showed the surface of the water to rise at the mean 
rate of 1 foot in 25 feet 48 hours after a rainfall of 
.87 inches, and the shape of the ground -water surface 
at the time in question is represented in Fig. 137. 
Of course, after the lapse of a longer interval of 
time the gradient here would have become less steep, 
just as was the case in the other instance cited. 

The subsoil in which these gradients were observed 
was a fine sand, in some places with grains so small 
as to approach the character of quicksand, and they 



436 Irrigation and Drainage 

represent conditions which are very common in locali- 
ties where underdrainage is needed, and, therefore, 
furnish a good basis upon which to form a judgment 
regarding the distance apart tile should be laid. 

DEPTH AT WHICH DRAINS SHOULD BE LAID 

The depth to which water should be lowered by 
drainage need seldom exceed 4 feet for ordinary farm 
crops, and often the lowering of the water surface 
may be less. 

It should be kept in mind that the level of the 
ground water changes with the season, and that many 
lands benefited by underdrainage are only too wet 
early in the spring, and if such lands are to be used 
for ordinary farm crops, it may only be needful to 
draw the water down so far as to make the surface 
dry enough to give good working conditions for the 
soil. In such cases, tiles placed 2% to 3 feet deep, 
rather than 3% to 4 feet, will usually be found suffi- 
cient. If the tiles are placed deeper than this, not 
only will there be a permanent lowering of the ground 
water, but the low stage will be reached so much 
earlier in the season that a smaller amount of the 
water flowing under the field may be used by the 
crop. 

Where fields are underlaid by sandy subsoils, it 
is quite important not to draw the water down far 
into the sand, because the height to which the water 
can be lifted rapidly in these by capillarity is quite 
short. To carry the groulid- water surface below this 



Distance Betiveen Brains 437 

limit not only lessens the amount of underflow which 
becomes available to the crop, but it also diminishes 
the amount of the heavy summer rains which the 
crop may use, because when the ground water is 
carried too low much of the water, in times of pro- 
longed heavy rains, may pass below the limit of root 
feeding before the crop has time to avail itself of it. 

DISTANCE BETWEEN DRAINS 

There are three chief factors which determine the 
proper distance between underdrains : (1) the freedom 
with which water may flow through the subsoil 
toward the drains, (2) the depth at which the drains 
are placed, and (3) the interval of time between 
rainfalls sufficiently heavy to produce considerable 
percolation . 

It should be clearly understood that it is the 
character of the subsoil, rather than that of the 
soil, which determines the rate at which water moves 
toward and into the drains, and it should be further 
understood that the subsoil which takes part in the 
lateral flow of the water may be several feet, even 10 
or more, below the level at which the drains are 
laid. 

[f, for example, the field to be drained has a 
rather close clay surface soil underlaid with two, three 
or four feet of heavy clay, which in turn is underlaid 
by a stratum of sand, then the movement of water 
from the surface toward and into the drains will 
be such as is represented by the arrows in Fig. 



438 Irrigation and Drainage 

136. That is, the water moves along the line of least 
resistance, no matter how circuitous or how long that 
may be. 

Where the cavities through which the water must 
flow are those due to the diameter of the soil grains, 



„, = /., 'A,' Sill- " ^ " ^//' ^'* r'/'-er/rs/z/s ^s'^i''/'.%~//''-^'^ ,,t'i:>-'c'''- 1-. ^'''' ''--'''1'"i'*'^-'"i'''3, 



'>1\N 



Fig. 136. Movements of water toward tile drains where heavy clay 
soils are underlaid with sand. 

the influence of size of grain on the rate of flow 
is such that the amount of water passing a given 
section under otherwise like conditions is somewhat 
nearly proportional to tiie squares of the diameters. 
This being true, if the effective diameter of the 
grains in the clay is .004 m.m., while that of the 
grains in the stratum of underlying sands is .07 
m.m., then their squares will be .0049 and .000016 
respectively, in which the ratio is nearly as 300 to 
1, so that the water would flow through the same 
length and section of sand about 300 times as rapidly 
as it would through the clay. 

It is also true that the lengths of the soil pores 
through which water flows decrease the rate in a ratio 
nearly proportional to the lengths, so that the sand 
column in the case cited, or, what is the same thing, 
the distance between drains, could be 300 times as 
great as with the clay and yet leave the rate of flow 
just as rapid. It is plain, therefore, that the move- 



Distance Between Drains 



439 



ment of the water in cases like that represented in 
Fig. 136 will be chiefly straight down through the 
soil and clay until the sand is reached, when the 
movement will be sideways toward the drains and 
finally upward, the water entering them chiefly from 
the under side. That is to say, the flow side wise 
through the clay toward the drains will be very slight 
indeed. 

Since the resistance to flow of water increases as 
the soil texture becomes more close, it is clear that 
the more open the soil the farther apart the drains 
may be placed. It is common to place lines of tile 
in underdraining varying distances apart, from 30 feet 
to 100 and even 200 feet. The reasons for these wide 
differences will be better understood after considering 
the way the ground -water surface changes under a 
tile -drained field following a rain. 




Fig. 137. The observed surface of the ground water in a tile-drained field 
48 hours after a rainfall of .87 inches. 



In Fig. 137 is represented the observed slope of the 
ground -water surface in a tile -drained field where 
the lines are placed 33 feet apart and between 3 and 



440 



Irrigation and Drainage 



4 feet below the surface. The conditions there shown 
had developed 48 hours after a rainfall of .87 inches, 
and the facts were obtained by sinking lines of wells 
at right angles to the drains, there being 3 wells 
between each pair. It will be seen that the height of 
the water on the crest between the drains varies, 
being much greater at 1 and 2 than elsewhere, and 
this is where the soil is more clayey, and so closer in 
texture. 

In Fig. 138 is represented the heights of the 
ground -water surface midway between the drains as 
they occurred 2 days, 2% days and 5% days after the 
same rain, and the differences in the steepness of the 
slopes in the several cases should be understood as due 
chiefly to differences in the size of the soil grains. It 
will be seen that after a period of nearly 6 days the 
surface of the ground water in the upper portion of 




Fig. 138. Changes in the level of the groundwater surface in tile-drained field. 



the field has become quite flat, having fallen below the 
level of the drains, and the gradient being reduced 
to 1 foot in 175 feet, while at the lower end, where 
the soil is heavier, the slope is still 1 in 27. 

Taking these two cases, let it be assumed that it 



Distance Between Drains 



441 



is desired to place the lines of tile close enough 
together, so that after 6 days following an inch of 
rain the water shall nowhere stand within 3 feet of 
the surface, and that the tiles are placed 4 feet deep. 
Since in the sandy subsoil of the upper part of the 




Fig. 139. Diagram of influence of distance between drains on 
depth of drainage. 

Held the mean gradient is 1 foot in 175, the lines 
of tile may, under such conditions, be placed twice 
this distance apart, or 350 feet, for then halfway 
between them the water would only stand 1 foot above 
the drains and hence 3 feet below the surface. But 
in the lower part of the field, where the soil is finer 
and where the observed mean gradient is 1 in 27, 
the lines of tile could only be placed 54 feet apart 
to ensure the same conditions. 

It was pointed out, in connection with Fig. 133, 
that the slope of the ground water toward the lake 
was at the rate of 1 foot in 24.4 early in the season, 
and later 1 foot in 35.86 feet, which would call for 
placing the lines of tile 50 to 72 feet apart. Refer- 
ring to the diagram. Fig. 139, it will be readily under- 
stood that when there is a drain at A and C only, 
the soil undrained must be highest at B, but if an 



442 Irrigation and Drainage 

intermediate line of tiles is placed at D, then the 
highest levels of the ground water would be found at 
E and F, farther below the surface, leaving the field 
better drained. It is very important that this prin- 
ciple be thoroughly grasped, because so many local 
conditions affect the depth and distance apart at 
which drains should be placed that no specific figures 
can be safely followed in all cases. It is generally 
true that in loose, loamy soils, and especially if under- 
laid by sand, good drainage will be secured with 
drains 100 feet apart and 3X feet deep. On heavier 
soils, they must be closer, and on more open ones 
they may be farther apart. 

In regard to depths of drains, it should be under- 
stood that the deeper they are placed the better work 
they do as a rule. If one soil has had its non- 
capillary pores "emptied to a depth of 4 feet, and 
another one only to a depth of 2 feet, the capacity 
of the former to store a heavy rain without over- 
saturation will evidently be greater than that of the 
latter, and hence the shallow drained fields will oftenest 
become over -wet in wet seasons. But the cost of 
digging 4 feet is much greater than 2X feet, the 
expense increasing faster than in proportion to the 
depth. 

In cold climates the tiles must be placed as deep as 
2 feet, to prevent their destruction by frost. Tiles 
are laid at a depth of 18 inches, but the practice is 
not only unsafe so far as destruction of the tiles is 
concerned, but not half the advantage can then be 
secured which they are capable of giving if laid deeper. 



Kinds of Drains 443 

KINDS OF DRAINS 

Drains are called closed or open, according as they 
are covered or not. There are conditions under which 
open drains or ditches should and must be used, but 
the closed forms are always to be preferred where 
thorough drainage and facility in working the land 
are desired. In the earlier practice of underdraining, 
before tiles were invented and manufactured on a 
large scale, various means were adopted to provide 
waterways through which the water could more readily 
drain away from the field. An early method was to 
place in the bottom of a ditch bundles of faggots end 
to end and then fill in, expecting the water to flow 
through the spaces between the faggots. Three 
slender poles were often used, one laid upon two 
others, thus forming a waterway ; or again, a single 
larger pole was split in two and these laid in the 
ditch side by side with the flat faces up. Two boards 
nailed together V-shaped and laid on the bottom of 
the ditch formed still another method of securing 
underground drains with wood. 

Stones were also used in various ways for the same 
purpose ; sometimes the bottom of the ditch was 
filled with small stones and then covered ; two rows 
of flat stones placed on edge to form a V opening 
downward, was another common plan. Two flat 
stones on edge, with a cover, were extensively used, 
and some even went to the trouble of paving the 
bottom of the ditch with flat stones and forming a 
closed stone drain by adding sides and top, which, 



444 Irrigation and Drainage 

when well done, was permanent and effective. Square 
blocks of peat have been grooved on one face and 
two of these placed together to form a tile, thus 
making a drain of another kind. Each of these 
methods of securing underdrainage involved much 
labor ; gave channels in which the water flowed with 
great resistance ; clogged easily, and while beneficial 
results invariably followed their use, they were neither 
wholly satisfactory nor permanent. 

When the manufacture of tiles from burned clay 
was begun, various shapes were adopted and abandoned 
for the present cylindrical type, which when well 
made and laid, has been found entirely satisfactory 
for the construction of closed drains. 

In more recent years an effort has been made to 
build a continuous line of tiles in the bottom of the 
ditch after it is dug and graded, using a concrete 
made from the best hydraulic cement, lime and sand^ 
The mortar, when made, is fed through a simple 
machine, which determines the size and shape of the 
tile, making it continuous, cylindrical and smooth on 
the inside. A trowel is used to cut the tile through 
to near the lower side with sufficient frequency to 
permit the necessary percolation from the soil, thus 
securing a drain with all joints perfect. The system, 
however, has not been sufficiently long in use to 
enable one to say how meritorious it is. 

Open surface drains, where they are permanent 
improvements, should, if possible, be made wide and 
with sides so gently sloping as not to be washed, and, 
if possible, so as to be grassed over and driveai through 



Kinds of Drains 445 

with mowing machine, both to keep it clean and to 
utilize the land for hay. In many flat prairie sec- 
tions there are " runs," "draws," ''sloughs" or natural 
waterways, through which the surface waters find 
their way, in the spring and at times of heavy rains, 
into drainage channels. Such drainage must usually 
be handled in surface drains, and even when the 
channel must in places have • a depth of three feet, 
it will be cheaper and far better in the long run to 
make them with sloping sides not steeper than 1 in 
2, or 12 feet wide at the top. If the work is done 
in the dry season, most of it can be accomplished 
with plow and scraper, and the earth moved back, 
smoothed down and seeded to grass so as to make 
it permanent, easily cared for, and not a serious 
obstruction. 

Where turns must be made in such drains, they 
should have a large curvature to prevent the water 
cutting into the bank. 

HOW WATER ENTERS TILE DRAINS 

The flow of water into the tile drains takes place 
through the walls of the tiles and through the joints 
made by abutting the ends together. It is a common 
impression that considerable space should be left 
between the ends of the separate tiles, in order that 
the water shall have opportunity to enter, and that it 
is quite necessary that the lengths of the tile shall be 
short, in order that there shall be sufficient space 
left for the passage of the water. 



446 Irrigation mid Drainage 

The facts are, however, that there is so ready a 
movement through the walls of ordinary tiles them- 
selves, and through the joints when they are made as 
perfect as possible, that every precaution should be 
taken in laying tiles to make perfect joints, in order 
that the silt and soil may be excluded, to prevent 
clogging the drain. 

A series of observations on 2 -inch Jefferson, Wis., 
tiles, relating to the rate of percolation through the 
pores in the walls, showed that under a pressure of 
23.5 inches the discharge per 100 feet into the tile was 
at the rate of 8.1 cubic feet during 24 hours. This 
occurred when the walls were surrounded by water 
only. When the tiles were covered with a fine clay 
loam, so that water had to flow through 3 inches of 
this soil to reach the tiles, the discharge was reduced 
to the rate of 1.62 cubic feet per 100 feet of tile in 
24 hours. It is plain, therefore, that with this poros- 
ity and with the openings at the joints, there is 
ample opportunity for the water to find its way into 
the drains after reaching them, and great pains 
should always be taken to make as close joints as 
possible. 

The use of collars to keep sediment from entering 
the joints is not a good practice. They will not, as 
a rule, fit closely ; they tend to encourage careless 
laying ; they increase the first cost, and the soil, if 
it works under the collars so as to fill the space, will 
retard the entrance of water into the drain. Tile well 
made, with ends square and whole, if properly laid, 
make a sufficiently close joint. 



Gradient of Brains 447 

THE FALL OR GRADIENT FOR DRAINS 

In most cases where drainage is required, the sur- 
face of the field is so flat that it is usually desirable 
to secure as much fall for the drains as it is prac- 
ticable to get, and so a careful study of the field 
should be made with a view to learning where the 
lowest land is and along what line the greatest rate 
of fall may be secured. This is a matter of the 
greatest importance, and the less the fall is the 
greater should be the attention given to it. If a fall 
of 2 inches or more in 100 feet can be secured, the 
conditions are favorable for good results. It often 
happens that less fall than this must be accepted, but 
this should be done only after careful leveling has 
proved a greater one impracticable. 

It will frequently happen that the line of lowest 
ground is quite tortuous, making the distance from the 
highest to the lowest point greater than to follow a 
straight line. When this is the case, and the fall 
very small, it may often be desirable to dig a little 
deeper in places, cutting off bends, and thus increase 
the fall. 

It will generally be true, however, that the main 
drain should follow the lowest line in order to secure 
as much fall for the laterals as possible, and this 
point is made the more important because the axis 
of each lateral should reach the main above its center, 
in order that water in the main shall not set back 
into it. 

Great pains should always be taken to get a per- 



448 



Irrigation and Drainage 



fectly uniform fall for the whole main or the whole 
of any given lateral, and the greatest care should be 
exercised to lay the tiles perfectly true to the grade 
when that has been determined. When this is done, 
there is the least tendency for sediment to lodge and 
clog the drain. 

It will not be possible in all cases to maintain a 
constant gradient, and when this is true it is best 
always to change from a less fall to one which is 
greater, because then any sediment which should be 

carried in the upper part 
of the drain will also be 
carried when the fall is 
^^ increased : but with the 
reverse conditions the 
lower fall must have a 
tendency to cause the 
drain to become clogged. 
Where a change from 
a larger fall to one less 
must be made, and the 
latter gradient is 3 inches 
per 100 feet or less, it 
will usually be prudent 
to place a silt basin where 
the change of grade oc- 
curs, as represented in 
Fig. 140. The silt basin, if the line of tiles is short 
and small, may be made by sinking an 8-, 10- or 12- 
inch tile below the level of the bottom of the ditch, 
and then notching another section of the same size, 




■.-=-^- 



Fig. 140. SUt basin. 



Size of Tile 449 

so that it may receive the drain from above and be- 
low. The sediment brought will then be dropped in 
the still water of the basin, and may be removed from 
time to time. To bring the silt basin to the top of 
the ground, it will be best to use one length of the 
glazed sewer tile, because this will not be injured by 
freezing. Where the line of tiles is large, and much 
sediment is likely to be moved, the silt basin should 
be dug larger and bricked up. Silt basins should be 
kept covered to avoid accidents, and especially in win- 
ter, to prevent injury to the tile by freezing. 

SIZE OF TILE TO USE 

It is not possible to give specific directions for 
selecting the sizes of tiles which are best, except where 
all the details regarding the field to be drained are 
known. It may be said, in general, that their capacity 
must be large enough to remove the excess of water 
of the heaviest rains which fall inside of 24 to 48 
hours, but how much this excess may be will vary 
between wide limits. 

If the tile are 3% to 4 feet deep, and the soil has 
been depleted of its moisture by a heavy crop, the 
cases are very exceptional when even a rainfall 
of 2.5 inches in 24 hours would produce much per- 
colation into the drains. It is the rains in the 
spring of the year which will most tax the drains, 
but it should be understood that so long as the 
water is moving quite rapidly through the soil it is 
sucking fresh air in after it, and there is little danger 

CO 



450 Irrigation and Drainage 

to crops, and for this reason mucli smaller tiles are 
permissible than would otherwise be the case. It is 
when the ground water in a cultivated field becomes 
stagnant or stationarj^ that poisonous principles are 
developed and suffocation for lack of air occurs. 

The greater the gradient or fall of the line of 
tiles, the greater will be its capacity and the smaller 
it may be for a given area. The area of cross- 
section of tiles increases in the ratio of the squares 
of the diameters ; thus for diameters of tiles of 2, 
3, 4, 5, 6, 7, 8 and 9 inches, the areas will be 4, 9, 
16, 25, 36, 49, 64^ and 81 square inches, and hence, 
when running full with the same velocity, their 
capacities would be in the relations of the second 
series of numbers. The friction on the walls of the 
tiles, and the eddies which the joints and other ine- 
qualities tend to set up, reduce the velocity in the 
small tiles more than they do in the large ones, 
hence doubling the diameter of tiles considerably 
more than makes its capacity four times as great. 

The longer the line of tiles the less it is able to 
discharge when running full, but just how much the 
capacity is decreased by the length cannot be simply 
or accurately stated. 

In speaking of the proper size of mains, C. G. 
Elliott* states : " For drains not more than 500 feet 
long, a 2 -inch tile will drain two acres. Lines more 
than 500 feet long should not be laid of 2 -inch 
tiles. A 3 -inch tile will drain five acres, and should 
not be of greater length than 1,000 feet. A 4 -inch 

* Practical Farm Drainage, p. 57. 



Size of Tile 451 

tile will drain 12 acres ; a 5 -inch, 20; a 6 -inch, 40 ; 
and a 7 -inch tile 60 acres." 

In the earlier practice of underdraining with cylin- 
drical tiles, sizes as small as 1% inches were used for 
the laterals, leading the water into the mains, but the 
general tendency has been to abandon the smaller 
sizes and to use nothing less than 3 inches in 
diameter, even for the laterals. The labor of making 
the small sizes is nearly as great as that required for 
those 3 inches in diameter, thus leaving the differ- 
ence in cost chieflj^ that of the extra amount of stock 
used in the manufacture. But the 3 -inch size is so 
much safer to use than the smaller ones that the 
latter should generally be abandoned. The most seri- 
ous objection to the small sizes is the great difficulty 
in laying them so exactly to grade as not to have 
them silt up. 

The sizes of mains and sub -mains, the sizes of 
laterals, the lengths of each size used, and the dis- 
tance between drains, can best be shown by citing a 
specific case where the conditions to be met have 
been considered in making the selections and adjust- 
ments. The case selected was laid out under the 
supervision of C. G. Elliott, C. E., and is an 80 -acre 
farm in northern Illinois, where the soil is a deep, 
rich, black loam, approaching muck in its lowest 
places, and underlaid at a depth of 2.5 feet with a 
yellow clay subsoil. The fall of the main drains in 
this case is not less than 2 inches per 100 feet, and 
that of the laterals is more rather than less. 

The diagram. Fig. 141, shows that the least distance 



452 



Irrigation and Drainage 



between laterals is about 150 feet ; an effort was not 
made to secure perfect drainage, but rather so nearly 
sufficient for ordinary crops as to make the increase 
in yield pay a fair return for the money invested. 




Fig. 141. Drainage system of 80 acres. Double lines represent mains ; single 
lines are laterals. Numbers give length of drains and diameter of tile. 
After C. G. Elliott. 



The double lines represent the mains and sub -mains; 
the single lines are laterals, and the numbers of three 
or more figures express the number of feet of each 
size used in the line against which they stand, while 
the single figures under these show the inside diame- 
ter of the tiles used. 

It will be seen that the main begins with 1,000 
feet of 7 -inch tiles, carrying the water from 80 acres 
of flat land surrounded by comparatively level fields ; 
next follow 1,200 feet of 6 -inch tiles, then 600 feet 
of 5 -inch, the line closing with 157 feet of 4 -inch 
tiles into which no laterals lead. 



Outlet of Drains 



453 



THE OUTLET OF DRAINS 

Great pains should be taken to secure a clear fall 
at the outlet of a drain, placing it, if possible, where 
it will always be above water, as represented at A, 
Fig. 142, rather than as at B. If the outlet is beneath 
water, the checking of the velocity of outflow will 
cause sediment to be thrown down, and will soon clog 
the main. Care should also be taken to so guard the 
outlet from the trampling of animals that they shall 





JVtffl .I^J' iiV .i.'V 'V '^l l''^ 'f* i*^ 


. .^ 


^^^^B 


[ 


E^^B 


=--5^ 


-i.^^^^ 



ll 




Fig. 142. Proper and improper outlet of drains. A, proper outlet ; B, improper 
outlet ; C, proper junction of lateral "with main ; D, improper junction. 



not break down the earth about it ; and against the 
effect of winter frosts and surface rains, tending to 
throw earth down over the mouth. 

In cold climates it will not do to terminate the 
main with the ordinary drain tile, as the action of the 
frost will soon crumble it down. A common plan is 
to make a wooden outlet, 16 feet long, out of 2 -inch 
lumber, thus holding the tile back beneath the sur- 
face sufficiently far to be safe against freezing. A 
much better termination of the main, however, and 
one which will be permanent, is glazed sewer tile, 
using not less than 10 feet of it. Lap -weld iron pipes 



454 



Irrigation and Drainage 




Fig. 143. Method of connect- 
ing lateral with main drain. 
After Jul. Kiihn. 



are also used for this purpose, but a section or two of 
the cast iron sewer pipe of the size of the main will 
be found better, because more durable. 

Where the laterals are connected with the mains, 
an effort should be made to introduce the branch 
above the axis of the main, and where there is fall 
enough to permit of doing so the method used exten- 
sively in Europe 
seems to be the 
best. This con- 
sists in perforating 
the top of the main 
and the bottom of 
the end tile of the 
lateral, placing the 
two openings together, as represented in Fig. 143, but 
first closing the ends of the tile with a stone and ball 
of clay. This arrangement allows the lateral to empty 
itself completely into the main, and prevents it from 
becoming clogged with sediment by the setting back 
of water into it. 

Where connection is made direct with the side of 
the main, it should be done by approaching at an 
angle down stream, as shown at C, Fig. 142, rather 
than as at D. This can be done, even if the lateral 
is at right angles to the main, by curving the ditch 
gently for a rod or more as the place of junction is 
approached. With this mode of joining, the least 
interference is brought about when the two currents 
unite and there is the least tendency to clog. 



Obstructions to Drains 



455 



OBSTRUCTIONS TO DRAINS 



In all cases where water flows through the drain 
during any considerable portion of the growing season, 
care must be taken to avoid the presence of trees 




Fig, 144. Showing roots of European larch removed from a 6-inch tile 
drain, which they had effectually clogged. 

anywhere within three or four rods of the line of tile, 
otherwise the roots will find their way into the drain 
through the joints, and there branch out into a com- 



456 Irrigation and Drainage 

plete mat of fine fibers, which will fill the whole drain 
and by arresting the silt moving with the water, com- 
pletely closes it. In Fig. 144 are shown two bundles 
of roots of the European larch which entered and 
completely choked a 6 -inch main lying 5 feet below 
the surface, and where the trees were standing 15 feet 
away from the line. There are but few trees that 
will grow in such places which can be trusted near 
the drain, but the willow, elm, larch or tamarack, and 
soft maple are among the worst. It should be under- 
stood that so long as the water in the drain is flowing 
it is highly charged with air, and trees may even bet- 
ter immerse their roots in this than in the more 
stationary water between the soil grains, hence they 
do so wherever opportunity is offered, unless the water 
should be poisonous. 

LAYING OUT SYSTEMS OP DRAINS 

In preparing to drain a piece of ground of con- 
siderable extent, careful study should always be given 
to the best way of laying out the system so as^ to 
secure the greatest fall and the most complete drain- 
age with the least digging and the smallest number 
of feet of tile at the lowest cost. To do this, care 
must be taken to avoid laying the lines so as to 
bring their influence within territory already sufficiently 
drained by another line ; to make the outlets and 
junctions as few as possible ; to avoid the necessity 
of the more expensive large sizes of tiles, and of dig- 
ging more deeply than is required for good drainage. 



Systems of Drains 



457 



In Fig. 145 are represented diagrammatically two 
ways of laying out a system of drains for the same 
piece of land. The area drained is about 14 acres, 
and with lines of tile laid 100 feet apart, system 
A requires 625 feet of 4 -inch and 3,020 of 3 -inch 
tiles, while that of B makes necessary only 550 feet 




Fig. 145. Two systems of laying out drains. 

of 4 -inch and 2,830 feet of 3 -inch tiles to drain 
equally well the same area. 

Where long lines of tile must be laid in which 
more than one size will be required, three systems 
have been adopted, that represented in A, Fig. 145, 
already described ; a second. A, Fig. 146, and a third, 
B, in the same figure. In the case of A, Fig. 146, 
covering a section 2,000 feet by 900 feet above the 



458 



Irrigation and Drainage 



«' 8' 3" 



3 3 3 



3 3 3 



N 



V 



3' 3' 3' 




S<.' 



line a a, there would be required 9,000 feet of 3 -inch 
tiles and 9,000 feet of 4 -inch tiles, with lines laid 
100 feet apart ; but following the second system, B, 

it would only be neces- 
sary to lay 3,000 feet of 
4-inch tiles, with 15,300 
feet of 3 -inch. At 1 
cent per foot for 3 -inch 
and 1.6 cents for 4 -inch 
tile, the difference be- 
tween the purchase price 
of the two sets of tile 
would be $33 in favor 
of the system B. The 
saving grows out of the 
fact that one line of 4- 
inch tile has "ample ca- 
pacity to drain not only 

Fig. 146. Two systems of laying out drains, ^^q strilD of ffrOUUd it 

traverses, but at the same time to discharge the water 
gathered by the three lines of 3 -inch tile emptying 
into it from the upper half of the field. 

It will be observed that in both diagrams the nine 
lines of tile have been brought to one outlet in the 
stream, rather than to make them all separate, as 
might be done in A, or to make three outlets, as could 
readily have been done in the case of B. To have 
finished the system with three outlets would not have 
been a bad or expensive plan, but to have as many 
outlets as there are lines of tile is not generally to 
be recommended. 



Intercepting Underflow 



459 



In actual practice, it will usually be found that no 
single system, such as has been represented, can be 
used alone, but rather a combination of them in 
various ways growing out of the irregularity of slopes 
and surface conditions. 



INTERCEPTING THE UNDERFLOW FROM HILLSIDES 

Cases are not infrequent where seepage from the 
high lands surrounding a flat area approaches so close 
to the surface at the foot of the rising ground that a 
single line of underdrains placed here at a good 





<^^ 
DW 







Fig. 147. Structural conditions producing swamp lands by underflow, and 
methods of intercepting the underflow. 

depth will so completely intercept the underflow as to 
make little other draining needed. The structural 
conditions which render underdrainage in such cases 
needful, the method of accomplishing it, and the 
underlying principle, are represented in Fig. 147. 

In this case the comparatively impervious rock 
bottom of the valley holds up the water and forces 



460 Irrigation and Drainage 

it to spread laterally and to underflow the low ground 
through the sandy stratum covered by the closer 
textured layer above, and to rise up through that 
soil layer, both by hydrostatic pressure and by cap- 
illarity, and thus keep it too wet for agricultural 
purposes. But when tiles are placed at A and B, 
at the foot of the high lands on both sides, the water 
can more easily escape into the drain than it can flow 
on through the sand stratum, and the result is, the 
pressure which before was forcing the water beyond 
A to the left and beyond B to the right may now be 
so nearly all absorbed by the flow of water into the 
tile drains that no more water reaches the flat land 
between them than is needed to meet the demands of 
vegetation and surface evaporation. The case is 
exactly similar to what is shown in the lower portion 
of the diagram ; here it is plain that if water is 
allowed to discharge at C and D nearly as fast as the 
pipes can bring it from the reservoir, there would 
be little left to pass on and escape through openings 
beyond, while if C and D are closed, the full pressure 
would operate to increase the discharge at lower 
openings, as at E. - . 

DRAINING SINKS AND PONDS 

It frequently occurs that low places are entirely 
surrounded by such high lands as to make it diflicult 
to provide an outlet for the surface water which col- 
lects in them, especially during the winter and early 
spring, keeping them too wet for agricultural purposes. 



Braining Sinks and Ponds 



461 



Where the water collecting in such places is 
largely from surface drainage, it is frequently possible 
to reclaim them by intercepting the water and divert- 
ing it around the sink in the manner suggested in 
Fig. 148, where A B 
represents a surface 
ditch taking the water 
from the higher land 
above. 

It is frequently true 
that such low places 
without natural outlets 
are underlaid with well 
drained beds of coarse 
sand and gravel, and 
in such cases, if the 
volume of water is not 
very large and if the 
bed of sand and gravel 
beneath it is thick and only 10 to 15 feet from the 
surface, a well sunk into the sand and gravel and 
stoned or bricked up may serve as an outlet for under 
or surface drains. 

Instead of curbing the well, it may be simply filled 
with loose stones to within 3 feet of the surface, 
covering these with smaller ones and finally with 
gravel and then sand, leaving the surface unobstructed. 

Unless the approach to this drain is so gradual 
that there is no danger of fine silt being deposited over 
it, it would be better to have this in a shallow sink 
surrounded by a slightly higher border, grassed over 




Fig, 148. Method of intercepting surface drain- 
age. A, B, surface ditch. 



462 



Irrigation and Drainage 



to hold back the water and throw down the sediment 
before reaching this place, as shown in Fig. 149, 
where a pit has been sunk into the porous gravel 
below and broadened at the surface to give more area 
for percolation through the finer material at the top. 
There are also represented lines of underdrains leading 
to the filter outlet, which might be needed in order to 
bring the land quickly into the best condition. If 
necessary, a line of such wells may be formed in a 
surface ditch or depression, and thus increase the 
capacity. 

THE USE OF TREES IN DRAINAGE 



In some instances where sinks without available 
outlets are to be drained, and where the method 
illustrated in Fig. 149 cannot be used, it is pos- 




Fig. 149. Method of draining sinks. 



I 



sible to throw up lands of higher ground with deep, 
open ditches between them, in the lowest portion of 
the sink, into which the other ground may be drained, 
and then plant water -loving trees, like the willow or 
larch, on the sides of the ditches, where, by their 



Draining SinJcs and Ponds 



463 



rapid growth and large evaporation of moisture 
through the foliage, considerable amounts of water 
will be removed. The most serious objection to the 
method is the fact that the trees will not render their 
greatest service early in the season, and may not fit 
the ground for early crops other than grass. 

THE USE OF THE WINDMILL IN DRAINAGE 

In such places as those under consideration in the 
last two sections, a good windmill may be made to 
drain a considerable area of ground where only the 




Fig. 150. Method of draining sinks by wind'power. 



underflow must be handled, and where the lift need 
not be more than 20 feet. 

If the water is to be raised to a level at which 
gravity will remove it, then a sump or reservoir 
should be sunk in the ground as near the place where 
the water is to be disposed of as practicable, deep 
enough to hold the drainage of two or three days 
when, for lack of wind, the mill may be idle. 

In order that the mill may work during the winter 
also in cold climates, the pump may be placed in a 



464 Irrigation and Drainage 

well, as in Fig. 150, into whicli tlie main drain, A, 
discharges, and from whicli there is an overflow, B, 
to the reservoir. The object of the well is to place 
the pump under conditions where it will not freeze in 
the severest weather, and thus prevent the ground from 
becoming over- saturated at any season. The water may 
be made to discharge through an under -ground drain 
connected directly with the pump, as at C, or a flume- 
box above ground may be used, as is most convenient. 

It might even be practicable to have this drainage 
water discharged into a reservoir and used for irriga- 
tion at a lower level during the dry season of the 
year, or it would be practicable to discharge it into a 
series of tiles laid 2 feet below the surface on a 
section of higher ground which is naturally well 
drained, and thus sub -irrigate this at the same time 
the low place is being drained, the two systems caring 
for themselves continuously. 

LANDS WHICH MUST BE SURFACE DRAINED 

There are many ancient lake bottoms now consti- 
tuting wide stretches of very flat country underlaid by 
heavy deposits of a very close lacustrian clay, through 
which water percolates with extreme slowness. Such 
lands must generally be surface drained, not only 
because it is difficult to find adequate fall for proper 
outlets for underdrains, but because the water would 
not reach underdrains quickly enough to meet the 
demands of crops unless the lines were laid closer 
together than could be afforded. 



Surface Drainage 465 

Even through a clay loam* it may require 24 hours 
for 1.6 inches of water to percolate through a stratum 
of soil 14 inches deep when the surface is kept under 
2 inches of water, and since the rate of percolation is 
somewhat nearly proportional to the length of the 
column, 2 days would be required for the same flow 
through 28 inches, and about 13 days through 15 feet, 
the distance the water would have to travel with 
underdrains placed only 30 feet apart. But the sub- 
soils of the lands in question are much closer than 
the loam cited, so that the best which has yet been 
done for such soils is to plow them in narrow lands, 
with the dead furrows extending along the slope of 
the fields in such a way that the excess of water may 
be quickly led away into the streams or open ditches. 

It is true that the tillage and heavy cropping of 
such soils, especially during dry seasons, tend to cause 
the clay subsoils to shrink into cuboidal blocks, and 
thus facilitate underdrainage ; but the long years 
which some of those lands have been under such 
treatment without marked amelioration appear to 
leave little hope of ever bringing them under thorough 
drainage in this way. 

There are other flat sections of country, with more 
open soils and subsoils, where sufficiently deep open 
ditches may be provided to serve as outlets for under- 
drains, and lands be thus thoroughly reclaimed. Such is 
the case in Illinois, and Fig. 151 represents six square 
miles of land treated in this way. In this figure the 
double lines represent deep open ditches, the single lines 

*The Soil, p. 171. 
DD 



466 



Irrigation and Drainage 



underdrains, and the small squares cover 40 acres 

each. 

Another drainage system of this sort in the same 

state is found in Mason and Tazewell counties, where 

by a cooperative plan the open ditches have been dug 




Fig. 151. Plan of drainage of lands of the Illinois Agi-icultural Company, 
Rontoul, Illinois. After J. O. Baker. The smallest squares are 40 
acres; double lines show open ditches; single lines are tile drains. 

and the expense divided among the landowners in 
proportion to the benefits derived. The work was 
begun in 1883, completed in 1886, and has 17.5 miles 
of main ditch 30 to 60 feet wide at the top and 8 to 11 
feet deep. Leading into these mains there are five 
laterals 30 feet wide at the top and from 7 to 9 feet 
deep, the whole system embracing 70 miles of open 
ditch, excavated for the express purpose of providing 
outlets for underdrains after the manner of Fig. 151. 



CHAPTER XIII 

PRACTICAL DETAILS OF UNDEBDEAINING 

To do the best work in underdraining requires not 
only a thorough knowledge of the principles, but an 
extended practical experience in laying out systems of 
drains. The man who has a thorough grasp of this 
business, and is experienced in laying out work and 
in the use of precise instruments for leveling and 
establishing grades, can, with the aid of eye and 
instruments, determine rapidly and accurately in the 
field the best place for the mains and sub -mains with- 
out making a detailed survey ; and where large areas 
are to be drained, especially if the fall must be small, 
it will usually be safer, better and cheaper to employ 
some man of experience who can be trusted to do the 
work of leveling, determining grades and accurately 
staking out ready for the ditcher both mains and lat- 
erals. 

Indeed, if a considerable amount of work is to be 
done, it will in most cases be better and cheaper in 
the end to entrust the whole job to a man who makes 
underdraining his business, and who employs and 
superintends his own crew of trained men. The mat- 
ter of ditching, even, is so much of an art that both 
intelligence and experience are required to do it well. 

(467) 



468 Irrigation and Drainage 

So true is this, that a good drainage engineer employs 
his men by the season or longer, if possible, and 
divides his work among them in such a way that each 
man does only one kind of digging. In this way each 
one becomes an expert in his place, doing more and 
better work with less effort than is possible in any 
other way. The man who finishes the bottom of the 
ditch and the man who lays the tiles must not only 
be skillful, but must be thoroughly trustworthy and 
patient, or faulty work will be done. The work 
is often so unpleasant, defects are so easily covered 
from inspection, and it will be so long before they 
could be discovered and the responsibility properly 
placed, that only men of peculiar fitness should ever 
be trusted with it. These men must be well paid, 
they must not be crowded, and there must be nothing 
else to take their attention. When the right sort of 
man has been secured for this work, and has been 
trained to it, he is far more to be trusted than almost 
any farmer, even for whom the work is to be done, 
because the farmer will have so many other things to 
take his attention, and he will be so anxious to have 
the job off his hands, that his patience will not per- 
mit him to take the necessary time to get every joint 
of the 100,000 just right before it is left. Important 
drainage work, then, should be left to expert men 
wherever practicable. 

It is very important that the farmer who has land 
to drain should thoroughly appreciate these essential 
conditions for safe work, not only to prevent himself 
from undertaking what he cannot hope himself to do 



Drainage Levels 



469 



well, but, what is more important, that he may be 
able to recognize the essential qualities in the man 
who will place the tiles, and satisfy himself that he 
possesses them. 

It will often happen, however, that drainage 
experts cannot be had, and there may be small areas 
to drain, involving relatively but small expense, 
where the farmer may do his own work or super- 
vise it. 

METHODS OF DETERMINING LEVELS 

Where the services of a man with instruments for 
determining levels for lines of drains cannot be had, 
there are various simple means for doing this work 
which may be employed n 

where great accuracy is not tjl 

required, and among these ^-' 



T^ 



perhaps the safest is the water-level, 
represented in Fig. 152. This may 
be made of %-inch gas pipe, with two 
elbows and a T, as shown in the sketch, 
the standard being sharpened by a black- 
smith or by inserting a wooden point. 
In the two elbows, which are about 
four feet apart, there are cemented 
short pieces of glass tube, or slender 
phials, %-inch in diameter, with the 
bottoms broken out, and provided with corks. To use 
the instrument, the tube is filled with water colored with 
bluing or ink, so as to show in the two tubes of 
glass, when the arm is horizontal. By forcing the foot 



I 



Fig. 152. 
Construction 

of a 
water-level. 



470 



Irrigation and Drainage 



of the instrument into the ground until it stands firmly, 
and removing the corks, the water will come to a level 
at once, so that if the operator stands back about 
four feet he may sight across the two surfaces to 
determine differences of level. If one uses this instru- 




« 



Fig. 153. Four forms of drainage levels, •mtli target-rods. 



ment with care, avoiding too long ranges, good work 
may be done with it. 

A carpenter^ s level is sometimes mounted in a 
similar manner and used, but it is not as safe a 
device, because the level itself is liable to be in error 



Use of Drainage Levels 471 

and there will be errors in deciding when it is set 
exactly, whereas the water-level can never be in error, 
and automatically adjusts itself at once, the only 
chances for error being in taking the sights. Other 
forms of drainage levels are represented in Fig. 153. 



LEVELING A FIELD 

If the field has but small fall, and is quite flat and 
even, so that the inexperienced eye fails to detect the 
direction of greatest slope, it will usually be safest to 
check it into squares of 50 or 100 feet, driving short 
stakes at the several corners, whose elevations may 
then be determined. To do the leveling, set the 
instrument at a. Fig. 155, midway between stations 
I-l and 1-2, having first provided a notebook, ruled 
as indicated in the table below. Turning the level 
first upon I-l, its distance below the instrument is 
read on the target -rod held upon that stake, and 
the result, 4 feet, is recorded in the table in the 
column headed "back-sight." The instrument is next 
directed to 1-2 and its distance below the level found 
to be 3.8 feet, which shows that its elevation must be 

4 ft.— 3.8 ft.=.2 ft. 

above that of station I-l. This reading of the target- 
rod is entered in the column headed "fore -sight." In 
the column headed " Elevation " the first station is 
given arbitrarily a value of 10 feet, as is customary 
to avoid minus signs, and on the same plan station 



472 Irrigation mid Drainage 

1-2 will have an elevation of 10.2 feet, as stated in 
the table. 

Table giving data obtained in leveling field, Fig. 156 

Station 
I-l 
1-2 
1-3 
1-4 
1-5 
1-6 
II-6 
II-5 
II-4 
II-3 
II-2 
II- 1 
III-l 
III-2 
III -3 
III-4 
III-5 
III -6 
IV-6 
IV-5 

The level is now moved to h and the distance of 
[-2 below it again measured and found to be 4.2 feet, 
which is entered in the notebook under " back-sight," 
and the instrument turned upon 1-3, where the read- 
ing is found to be 4 feet, and entered in the table. 
The difference between the fore- and back-sights, 
placed in the column headed " Difference," shows how 
much higher one station is than another, and when 
the first is added to the elevation above datum, 10 



Back-sight 
4 


Fore-sight 


Difference 


Elevation 
10 


4.2 


3.8 


.2 


10.2 


3.8 


4 


.2 


10.4 


4 


3.6 


.2 


10.6 


3.9 


3.8 


.2 


10.8 


4 


3.7 


.2 


11 


3.8 


3.98 


.02 


11.02 


3.9 


3.995 


.195 


10.825 


4 


4.095 


.195 


10.63 


4.1 


4.19 


.19 


10.44 


3.9 


4.26 


.16 


10.28 


3.8 


3.98 


.08 


10.2 


4 


3.6 


.2 


10.4 


3.9 


3.96 


.04 


10.44 


4.2 


3.775 


.125 


10.565 


4.1 


4.045 


.155 


10.72 


3.8 


3.93 


.17 


10.89 


4.1 


3.625 


.185 


11.075 


4 


4.185 


.085 


11.16 




3.84 


.16 


11 



Use of Drainage Levels 473 

feet, at station I-l, it gives 10.2 feet, or the 
elevation of station 1-2 above the same plane The 
difference, .2 feet, between stations 1-2 and 1-3 added 
to the elevation of 1-2, gives 10.4 feet, or that of 
station 1-3. In this manner the instrument is moved 
forward step by step until measurements from e have 
been made, when the level is next set at /, and back- 
and fore-sights taken and entered, as shown in the 
table, so as to connect the observations of the first 
line with those of the second line of stations 

Proceeding to g, the steps described are repeated 
by moving back through h, i, j, k and I U> m, and so 
on until the elevations of all the stations have been 
determined and entered in the table. It will be 







O-'-,..^.-.'. <3". 






Oii^^r'-pj4 



Fig. 154. Method of leveling. 

Observed that when proceeding from higher to lower 
levels It IS necessary to subtract the value in the 
column of diiferences from the elevation of the station 
preceding it, in order to obtain the elevation of the 
station for that difference. 

In Fig. 154 is shown the method of leveling 
described where the different positions of the level 
and of the target along one line are shown in ele- 
vation. 



474 



Irrigatiofi and Drainage 



LOCATION OF MAIN DRAINS AND LATERALS 

After the notes of the field leveling have been 
obtained, and the elevations computed from them, 
these may be transferred to a diagram of the field, as 



.ni07-5 1-11.0 2 _ fu- - .U .0.:^ 

1,89 lolsSS ^1 ^8^=^ 




Fig. 155. Leveling for a contour map of field to te drained. 

in Fig. 155, where they will show at a glance the' 
slope of the surface, and where the mains must be 
placed in order to secure the greatest fall, both for 
them and for the laterals. It will be seen that station 
VI -6 is the highest point in the field, while I-l is the 



Location of Mains and Laterals 



475 



lowest, and that if a straight main were laid through 
these two points it would be given the course along 
which surface water would naturally flow, which is 
also the direction of steepest slope. 

The dotted lines in the figure are contours, or 



\.-x 


' \ 


V>-' 












\^ 




\ ^"^ \. 










ll.tt 






\ / X 






_, - — — 




' 


/ \^ 




















/ \ X 


__, ^■" 










K 




k. 








lO.f 


^ N. / 


\ 


\ ^ \ X 




, . 


— 






\ 


\^ \ \ --^ 


kr' 










\ 


^ \ \,^ x. 








b. '^ 


\ 


/ \ \ ^ X 










\ 

/ 


\ \ X \ ^ 


'v 




10.6 






\ X \ \"'^ 


k. 




/ \ 
/ \ 


/ \ 
/ \ 


\ X Xs^X; X X 




/ 
/ 


\ 


X \ X \ \ 


J0.4 




\ 






/ 

/ 
/ 

t 


\ 


/\ \/ 


\|,X' \ 




1 
1 




~~7^k \. / Nv 






/ X X \ / \ \ 




1 




'X ,N \ ^ X \ 




1 




/ \. / \ \ / \ \ 




1 






/\ V"X 


"~~"^ 


1 


; 


\'' \ 




/ 


7x X'' ^ ''^ 






/ 




XX \ 


^ 




1 

1 

1 


1 \/ 


o] 


1 — 


to' x*! ', ..i^W^ 


r-i 


o 


O , C) 1 — ?S^^&!»— 1 _*^^^^ 


iHl 


u 


^ \ "^J^^^^^^^^^^s*"^^ 



Fig. 156. Arranging drains to secure the maximum fall. 

lines of equal elevation, and as in this case these 
are circumferences of circles with centers at station 
I-l, it is clear that the shortest distance between any 
two contours will be measured along their radii, and 
hence, that there also will be the greatest fall. Since 
the diagonal line from VI- 6 and the lines I and 1 



476 Irrigation and Drainage 

are each a radius of a circle from the same center, 
I-l, the fall along each will be thej'same, namely, 2.4 
inches per 100 feet ; hence, to drain this piece of 
land, three mains may occupy the positions of these 
three lines, meeting at station I-l. But if laterals 
are to be placed 100 feet apart, these could be given 
about as great a fall if they were to connect with the 
diagonal as a main, and take the positions indicated 
by the two right -angle systems of lines in Fig, 155, 
I, II, III, IV, V, representing laterals on the upper 
side of the main, and 1, 2, 3, 4, 5 on the lower. If, 
however, drains were to be placed 50 feet apart, then 
the most rapid fall could be secured and the least 
amount of tile would be required, by arranging the 
laterals as shown in Fig. 156, where the same area 
is represented with the contour lines drawn 100 feet 
apart horizontally and .2 foot vertically, as they are 
also in Fig. 155, and where the heavy ruling repre- 
sents main drains and the light ones laterals. 

STAKING OUT DRAINS 

When the location of mains and laterals has been 
determined, the next step in the practical work is 
staking out the drains. There are various methods of 
doing this, but one of the best is as follows : Short 
stakes, about 8 to 10 inches long, called grade pegs, 
are provided, and another set upon which records can 
be made with lead pencil, longer than the others, and 
called finders. With a tape line or chain and hatchet, 
the work begins by laying off along the main, begin- 



Laying Out Drains 477 

ning at the outlet, intervals of 50 feet, at each of 
which a grade peg is set about 12 inches to one side 
of the center of the ditch, where they will not be 
disturbed, driving them down flush with the surface 
of the ground. About 6 inches farther back from 
the line of the ditch a finder is also set. Sub -mains 
and laterals are staked off in a similar manner, and 
when this is done the work of leveling for digging 
the ditches may begin. 

DETERMINING THE GRADE AND DEPTH OF 
THE DITCHES 

The determination of the levels of the grade pegs 
should begin at the outlet of the main, and proceed in 
the manner already described in leveling the field, enter- 
ing the figures in a table prepared in the notebook, 
as shown below : 

Table showing field notes for determining depth of ditch and grade of drain 

Depth of 
Station Back-sight Fore-sight Difference Elevations Grade line ditch 



Outlet 


7 


.... 


. . . 


7 


7 








4 


.... 


3 


10 


7 


3 


50 


3.97 


3.87 


.13 


10.13 


7.12 


3.01 


100 


4.2 


3.83 


.14 


10.27 


7.24 


3.03 


150 


4.1 


4.08 


.12 


10.39 


7.36 


3.03 


200 


3.95 


3.99 


.11 


10.5 


7.48 


3.02 


250 


3.87 


3.82 


.13 


10.63 


7.6 


3.03 


300 


4 


3.69 


.18 


10.81 


7.72 


3.09 


350 


4.25 


3.83 


.17 


10.98 


7.84 


3.14 


400 


4.08 


4.1 


.15 


11.13 


7.96 


3.17 


450 


4.05 


3.96 


.12 


11.25 


8.08 


3.17 


500 


3.97 


3.95 


.1 


11.35 


8.2 


3.15 


550 


3.75 


3.97 


. . . 


11.35 


8.02 


3.03 


600 


• ■ • . 


3.74 


.01 


11.36 


8.44 


2.92 



478 



Irrigation and Drainage 



Referring to 157, which is a profile of the data in 
the' table, A is the outlet of the drain; the first stake 
set is marked 0, the second 50, etc., up to 600, the 
numbers expressing the number of feet from the out^ 
let. The datum plane is chosen 10 feet below the 

oAft 250 300 »50 400 450 500 550 600 
50 100 150 200 ~ - r-, n r-1 r-i r-, m 




Fig. 157. Determining grade line and depth of ditch. 

surface of the ground, at station 0, and the ground 
here is 3 feet above the bottom of the drain, which 
leaves the outlet 7 feet above datum, as stated in the 
table, which is also the elevation of the grade line at 
this place. 

Referring to the table, in the column of elevations 
it will be seen that the surface of the ground at 600 
feet from the outlet is 11.36 feet above datum plane, 
while the outlet is 7 feet above, making a total fall of 

11.36—7 = 4.36 feet. 

If it is decided to give the drain a fall of .24 foot, 



Laying Out Brains 479 

or 2.88 inches per 100 feet, it will be necessary to place 
the bottom of the tile, at 600 feet from the outlet, 

6 X. 24 = 1.44 feet 
higher than the outlet; that is, 

7+1.44 = 8.44 feet 
above datum plane ; but as the surface of the ground 
at the 600 -foot station is 11.36 feet above this plane, 
as given in the table, it is clear that the ditch must 
be dug at this place 

11.36 — 8.44 = 2.92 feet 
deep, as written on the finder stake in Fig. 157, and 
as given in the table of field notes in the column 
headed "depth of ditch." 

Since the grade line rises .24 foot per 100 feet and 
.12 foot per 50 feet, the data in the table under 
"grade line" are obtained by adding .12 foot to 7 
feet, the distance of the outlet above datum, for the 
50 -foot station ; twice .12 foot to the second or 
100 -foot station, etc. 

The numbers in the column of differences are 
obtained by subtracting the front -sight from the back- 
sight, taken with each setting of the level, and these 
differences, added to the height of the lower station, 
give the elevation of the higher station above datum 

plane, thus: 

4 — 3. 87 =.13 feet; 

and this amount, added to the height of the back- 
sight station, gives 

10 +.13 = 10. 13 feet 

as the elevation of the 50 -foot station, and subtract 



480 Irrigation and Drainage 

ing from this elevation that of the ^bottom of the 
proposed ditch at this place, there is obtained 

10.13—7.12 = 3.01 feet, 

or the depth which the ditch must be dug at this 
station, and it is the custom to write these depths on 
the finder stakes, to serve as the guide to the ditchers 
in digging, as represented in Fig. 157. 

These values are given in feet and hundredths 
rather than in feet and inches, because it is much 
simpler to make the calculations in this way. The 
target -rod should be made to read in this way rather 
than in feet and inches, and if the farmer makes his 
own this may readily be done by first dividing the rod 
into feet and then, taking a pair of dividers, set them 
so as to space off ten equal divisions within each foot. 
The tenths of a foot may then be subdivided in the 
same manner into ten equal divisions, or hundredths 
of a foot. 

Where a level without a telescope is used, the 
measuring rod should be provided with a sliding 
target, as shown in Figs. 153 and 158, which may be 
moved up and down by the target man, as directed, to 
mark the elevation indicated by the instrument. The 
best target is provided with an opening in front of the 
rod, which permits the figures to be seen at the junc- 
tion of the cross lines of the target. 

In taking the elevations, the target -rod should 
always be set upon the grade peg, and all subsequent 
measurements in digging should also be made from 
these pegs, which are driven in flush with the surface, 



Changing Grade 481 

not only that they may represent its true level, but 
also to avoid danger of the pegs being disturbed. 



MORE THAN ONE GRADE ON THE SAME DRAIN 

It very frequently happens that the surface of the 
land to be drained is such as to make it impracticable 
to lay out the whole of a main or of a lateral with the 
same amount of fall throughout. Let it be supposed 
that at the end of the 600 feet represented in Fig. 
157, the ground continued rising backward at a slower 
rate for 500 feet more, as the figures show it had 
begun to do, and that in the 500 feet the rise was 
only six inches. In order to avoid digging too deeply 
in some portions of the line, or of placing the tile too 
close to the surface at others, it is necessary to change 
the grade, and the new grade will be found by divid- 
ing the total fall .5 feet by 5, the number of 100 feet, 
which gives .1 foot, and half this amount instead of 
.12, is what would be added at each 50 -foot station, 
in order to get the new grade line elevations. 

DIGGING THE DITCH 

It has been pointed out that practice is required 
in order to dig a ditch well, rapidly and easily. It is 
further necessary to have suitable tools for the pur- 
pose. First in importance is the ditching spade, two 
forms of which are represented in Fig. 158. These 
spades have blades 18 inches long, narrower than the 
common tool, and strongly curved forward, to give 



482 



Irrigation and Drainage 



greater stiffness, and to permit them to be thin and light. 
The solid blade gives better satisfaction generally than 
the other form shown in the cnt. 

Besides the spade, there must also be the tile hoe, 
or scoop, for cleaning out and grading the bottom of 




Fig. 158. Some drainage tools. 



the ditch, fitting it for the tile, different widths being 
used for different tiles, as shown in the cut. Some of 
these scoops are made with adjustable handles, per- 
mitting the blade to be set at anj- desired angle, so 
as to be used from the last spading of earth in the 
ditch or from the top. 



i fl^A 




m 




Fig. 159. Commencing n ditch. 




Fig. 160. Removing the last two spadingsfrom the ditch. 




Fig. 161. Bringing the ditch to grade line with tile hoe. 




rig. 162. Placing tile with tile hook. 



Digging the Bitch 485 

When digging begins, a strong line is stretched 
about 4 inches back from the side of the ditch and a 
harrow cutting made, seldom necessarily more than 12 
inches wide, as shown in Fig. 159, the effort being to 
remove as little earth as possible. The sides are cut 
true to line to begin with, and maintained so to the 
bottom, in order that a straight bed may be finished 
to receive the tiles. When the ditch is deeper than 
4 feet, it is necessary to make it a little wider at the 
top but not much, as will be seen in Figs. 160 and 161, 
where the first shows the men in line cutting a ditch 
4.5 to 5 feet deep, while the second figure shows 
another man following with the tile hoe, working from 
the top, cleaning out the bottom and bringing it to 
grade line. The line which is seen in Fig. 161, 
stretched along the ditch, is placed parallel with the 
grade line some whole number of feet above it, and is 
used by the man to measure from when finishing the 
bottom. The line is a slender but strong cord, w^hich 
may be stretched tightly, so as not to sag. In the 
case in xiuestion, the man determined his depths with 
the measuring rod in the foreground, his long expe- 
rience enabling him to dispense with a sliding arm, 
which is generally used, forming a right angle with 
the rod and long enough to reach the grade line. In 
Fig. 162, the last man is using the tile hook, shown 
second from the right in Fig. 158, to lay the tile in 
place. This ditch, although for 6 -inch tile, laid 4.5 
to 5 feet deep, is scarcely more than 15 inches wide at 
the top, as the length of the tile placed across the 
ditch for a scale shows. 



486 Irrigation and Drainage 

These men never get into the bottom of the ditch, and 
3^et the tile are laid with great accnracy and turned 
about with the hook until close fitting joints are secured. 

It is preferred by some to lay the tile by hand, 
the operator standing on the tile, which are covered 
with earth 4 to 6 inches deep as rapidly as placed, 
using the wet claj' last thrown out, or some taken 
from the side of the ditch, which is thoroughly 
worked in about the tile, care beings taken not to get 
them out of alignment. B\^ whatever method the tile 
are laid, the greatest care must be observed in secur- 
ing close joints and in covering them, to see that 
they do not become displaced. 

The work should begin at the outlet with the la}'- 
ing of the main, and proceed backward to the first 
lateral, when this should be started and the junction 
made at once, laying two or three tile of the lateral 
before proceeding further with the main. If junction 
tile are not used, the opening through the w^nlls for 
the connection is made with a small tile pick with a 
sharp point, and great care should be taken to make 
a close connection by shaping and fitting both pieces 
together and covering the joint with stiff clay, well 
packed about, it. 

If for any reason the line of tile is left, as at 
night or over Sunday, the open upper end should be 
plugged with a bunch of grass or covered with a 
board, to prevent dirt being washed into the line in 
case of rain. When the end of the line is reached, 
the opening of the last tile should be closed with a \ 
brick or stone. 



Fining the Ditch 



487 



It is veiy iniportjxut to get the dirt well filled in 
about the tile and at the same time well packed, in 
order that large open water channels maj^ not exist 
through which streams of water may flow in sufficient 
volume to carry silt into the tile through the joints, 
and also in order that open channels maj^ not exist 
outside aud under the tile along which streams may 
gather and flow. The clay soil, usually last taken out 
of the ditch, is the best for this purpose. 






Fig. 163. The start and finish of tile draining. 



Various methods of filling the ditch, after the first 
covering of the tile, are in use, and Fig. 163 repre- 
sents one, where a plow is drawn by a team working 



488 Irrigation and Drainage 

on a long evener. Where a road scraper is available, 
this makes a good tool for finishing up with after 
the line is filled enough to cross with the team. 
Another method of filling, where the work is done by 
hand, is to tie a rope to the handle of a broad scoop, 
which is worked by a man across the ditch, while 
another guides the shovel as though not assisted by 
the man with the rope. In this way the dirt is filled 
in rapidly. 

Still another method is to use a team on a wide 
board scraper provided with handles, drawing it toward 
the ditch, the team being attached by means of a long 
rope and working on the opposite side of the ditch, 
the filling being done by driving forward and then 
backing, the man holding the scraper pulling the tool 
back. 

When quicksand is encountered in laying tile, it 
may be necessary to brace the sides of the ditch to 
prevent caving, when digging. This may be done by 
driving sticks in between two pieces of board, thus 
holding them against the opposite sides of the 
ditch. It is occasionally true that the bottom is so 
soft from quicksand that the tile cannot be laid to 
grade, and in such cases a fence board may be 
placed on the bottom and the tile laid upon this. 
In other cases the ditch may be dug a little below 
grade line, and the bottom covered with clay, if that 
is available, so as to form a foundation upon which 
to place the tile. It will sometimes be true that a 
quicksand spot will become sufficiently firm to lay 
across if it is permitted to drain three or four days, 



Cost of TJnderdraining 489 

and the level of the ground water be thus lowered. 
The reason for this is that the quicksand character 
is due to the water being forced up through the fine 
sand, which has little adhesion between its grains, 
and the water tends to float the sand, thus causing it 
to run with unusual freedom ; but when the water is 
given time to drain away, so that the sand is no 
longer full of it above the bottom of the ditch, it 
becomes firm, and the tile may then be laid. 

COST OF UNDERDRAINING 

It is not possible to give the cost of draining land 
without knowing all of the details which go to make 
up the total expense ; but certain general statements 
may be made, which will enable any one to compute 
for himself what the cost is likely to be. 

In the case represented by Figs. 159 to 163, the 
work was done by a professional drainage engineer at 
an average cost of $3 per 100 feet for digging and 
laying the tile, and 30 cents per 100 feet for filling 
the ditches, thus making the labor after the tile had 
been placed upon the ground $3.30 per 100 feet, 
including the board of the men. The ground drained 
in this case was such as to represent about average 
conditions, where the spade may be readily put into the 
soil with the pressure of the foot, where no stones or 
quicksands are encountered, and where the main has 
a depth of 3 to 5 feet, and the laterals an average 
depth of 3 feet. In the case represented in Fig. 141, 
Mr. Elliot gives the cost of the different items as 
expressed in the table which follows: 



490 



Irrigation and Drainage 







Cost of main drains per 1,000 feet 




No. of feel 


Size 


Digging, laying 
Depth Tile and filling Total 


Cost 
per rod 


1,000 


7 in 


5 ft. $60.00 $37.20 $97.20 


$1.60 


2,700 


G in. 


5 ft. 40.00 36.60 206.82 


1.26 


850 


5 in. 


4 ft. 30.00 24.20 46.07 
Cost of lateral drains 


.89 


8,280 


4 in. 


3.5 ft. $20.00 $20.00 $331.20 


$0.66 


7,030 


3 in. 
Total. . 


3 ft 13.20 20.00 233.40 


.55 




$914.69 





It will be seen from this table that the cost of 
draining 80 acres, as represented in the figure, averaged 
$11.43 per acre where everything was counted. It 
will be seen that the cost of mains was from two to 
three times as much as laterals of 3 -inch tile, and 
hence, that the larger and longer the mains must be 
made the more expensive relatively the draining will be. 



Cost of ynains per 100 feet 



5-incli 



6 -inch < 



7- inch < 



8-ineh < 



th of ditch 


Cost of digging 
and laying 


Cost of tile 


Cost of filling 
ditch 


Total cost 
per 100 feet 


3 feet 


$1.50 


$3.00 


$0.30 


$4.30 


4 feet 


2.00 


3.00 


.42 


5.42 


5 feet 


3.00 


3.00 


.60 


6.60 


6 feet 


4.50 


3.00 


.75 


8.25 


3 feet 


1.50 


4.00 


.30 


5.80 


4 feet 


2.10 


4.00 


.42 


6.52 


5 feet 


3.00 


4.00 


.66 


7.66 


6 feet 


5.10 


4.00 


.78 


9.88 


3 feet 


1.80 


6.00 


.36 


8.16 


4 feet 


2.40 


6.00 


.48 


8.88 


5 feet 


3.00 


6.00 


.72 


9.72 


6 feet 


5.70 


6.00 


.90 


12.60 


3 feet 


1.92 


8.50 


.42 


10.84 


4 feet 


2.58 


8.50 


.54 


11.62 


5 feet 


3.90 


8 50 


.78 


13.18 


6 feet 


6.00 


8.50 


1.00 


15.52 



Peat Lands 491 

We quote this table regarding the cost of mains, 
as estimated by Mr. Elliot, where the price paid for 
good ditchers is $2 per day; but in this estimate the 
board of the men is not included, neither is the cost 
of hauling the tile from the station to the field. 

This same writer estimates the cost of 3 -inch lat- 
erals, placed 3 to 3.5 feet deep, at $2 per 100 feet for 
the digging, lajdng and filling, and tile at the present 
writing would add another dollar, making $3 per 100 
feet, not including board or hauling the tile. 

The cost per acre will, of course, vary with the 
distance between lines of tile, and will increase very 
nearly in proportion to the number of feet of tile 
used. 

PEAT LANDS 

There are many marshes underlaid by beds of peat 
not yet well rotted ; peat so free from silt and so 
fibrous in texture that when dry it could be used for 
fuel. Where fields are underlaid by such beds having 
a depth of three or more feet, they are not likelj^ to 
become at once productive if well drained. On the 
other hand, where the peat deposit is only from 6 to 
18 inches deep, there are likely to be better returns 
from thorough drainage. 

In the first class of cases referred to, underdrain- 
ing is not usually to be recommended as the first 
step toward improvement. The difficulty lies in the 
fact that when peat beds are drained they shrink 
greatly in volume, thus lowering the surface in a 



492 Irrigation and Drainage 

marked degree, and if underdrains were laid at once, 
the lines of the tile would ultimately be found too 
close to the surface. It is, therefore, usually better 
in such cases to drain first with open ditches, plac- 
ing them where ultimately they may be deepened 
and converted into underdrains. The surface ditch- 
ing will dry out the marsh to a considerable extent, 
and permit the needed decay and shrinkage of the 
peat to take place, although several years may be 
required for this. 

If the peat is very coarse and thick, and if little 
vegetation grows upon it, it may be well to burn it 
over several times when not too dry, in order to 
increase the silt and ash in the soil and to hasten 
the shrinkage. The ash thus formed will so much 
improve the texture of the surface as to very mate- 
rially assist in getting a crop started upon the area. 

It is very important to get a crop started upon the 
soil as soon as practicable, because this greatly facili- 
tates and hastens the rate of decay. This should 
be done, even though it may not be remunerative in 
any other way than that of improving the texture of 
the soil. 



INDEX 



Acre-foot, 239. 

Acre-inch, 239. 

Aermetor, windmill, 313; pump, 316. 

Air, in the soil, 7, 182; humidity, 40, 44, 
50; required by clover, 49; by corn, 
185; interfei'es with percolation, 333; 
need of in soil, 182, 370, 418; lack of 
in puddled soil, 334 : changes in tem- 
perature and pressure influence ven- 
tilation, 420. 

Alfalfa, roots, 233; irrigation, 237, 346, 
348 ; utilizing waste water, 379. 

Algeria, irrigation, 85, 238 ; dvity of 
water in, 212; artesian wells, 85. 

Alkali, composition, 278 ; accumulation, 
223, 266, 270, 272, 274, 284; cause of in- 
juries, 270, 416; accumulation by in- 
tensive farming, 274, 284; amounts in- 
jurious, 275, 278; develops soonest in 
clay soil, 286 ; correction by land 
plaster, 280, 284, 287; distribution in 
soil, 282; influenced by tillage, 284; 
influenced by roots, 284; cause of 
abandonment of ancient irrigation 
systems, 289; geographical distribu- 
tion, 272; formed by canal seepage, 
294 ; soils which soonest develop 
alkali, 286 ; cause of puddling, 335. 
Alkali lands, 269, 416; alum spots, 269; 
soluble salts, 269, 276 ; character of 
vegetation, 281; land plasters, 280, 284 ; 
improvement by drainage, 223, 284, 
288; ultimate remedy drainage, 288. 
Alkali salts, 266; kills barley, 276; see 

Alkali. 
Alkali water, unsuitable for irrigation, 
266, 284, 285; correction before use, 
287. 



Alum spots, 269. 

Animal power for irrigation, 328. 

Ants, work in soil ventilation, 419. 

Apple, roots, 231. 

Argentina, irrigation,^87. 

Arid climate, efficiency of rainfall, 4, 
104; accumulation of alkalies, 272. 

Armenia, irrigation, 84. 

Artesian wells, in Sahara. 85; in Ha- 
waii, 86. 

Assyrian irrigation, 67. 

Australia, irrigation, 81. 

Austria-Hungary, irrigation, 75. 

Baker, J. O., 466. 

Barker, F. C, 236. 

Barley, water used, 21, 24, 34, 46, 235 
available rainfall, 124 ; yield, 129 
yield increased by irrigation, 110 
second crop, 130, 179 ; number of irri- 
gations, 235; on alkali lands,'276. 

Barrens, 114. 

Basin irrigation, 387, 390 ; Egypt, 288. 

Bavaria, irrigation, 76. 

Bear valley dam, 302. 

Belgium, water-meadows, 362. 

Blackberry irrigation, 383. 

Black marsh soil, mulches, 201 ; alkali, 
269, 273; vegetation, 281. 

Boussingault, 49. 

Breathing of plants, 47, 182; pores, 51. 

Bucket pump, 316, 319, 325. 

Busca canal, 210. 

Cabbage, irrigation, 387 ; yield in- 
creased by irrigation, 110; effect of 
supplementing rainfall in Wisconsin, 
175. 



(493) 



494 



Index 



Canal, ancient, 67; Busea,210; Ceylon, 
81; Doab, 80; Egj-ptian, 68; Eu- 
phrates, 68; Forez, 72 ; Gattinara, 
210; Great Imperial, 71; Ganges sys- 
tem, 80; India, 79 ; Indus valley, 81; 
Ivrea, 209; West and East Jumna, 80; 
Kern Island, 292 ; Nahrawan and 
Dyiel, 69; Nira, 78 ; Santa Ana, 297; 
Sirliind,291; Soaneoircle, 80; cement, 
300, 412 ; dangers, 295 ; sewage, 410, 
412; stone, 410. 

Canvas dam, 339, 341, 355. 

Cape Colony irrigation, 85. 

Capillary spread of water, 161, 330, 375. 

Capillarity, rate in sand and loam, 148. 

Carbon dioxide, consumed by clover, 
49 ; possible insufficiency in close 
planting, 185; in soil ventilation, 419; 
consumed by maize, 185. 

Carpenter, L. G., water-meadows, 219; 
seepage from reservoir, 323 ; water 
divisor, 245. 

Catcb crops, 152. 

Celery, irrigation, 385. 

Ceylon, irrigation, 81. 

Checks, 345, 348, 350. 

Check ridges, 346, 348. 

Child, J. T., 83. 

China, irrigation, 71, 82. 

Chinese irrigation, 387. 

Clay soil, develops alkali, 286. 

Climate, arid, 4, 104; for irrigation 
practice, 89; for sewage irrigation, 
404; lainfall needed for humid and 
subhumid, 121. 

Clover, water used, 24, 34, 36, 41, 46 ; 
irrigation, 110, 130, 179 ; on sandy 
soil, 169. 

Colmatage, 94, 261. 

Corn. See Maize. 

Cotton, duty of water, 211. 

Craigentinny meadows, 16, 92, 254, 403. 

Cranberries, duty of water, 220; irriga- 
tion, 365. 

Cranefield, F., irrigation with cold 
water, 251. 



Crops, yields, 125, 126, 174, 175, 177, 179, 
187, 190, 210 ; for sewage irrigation, 
409, 411. 

Cucumbers, irrigation, 388. ' 

Cultivation. See Tillage. 

Cultivator, orchard, 381; potatoes, 354. 

Croyden, sewage irrigation, 411,412, 413. 

Dam, submerged, 305; canvas, 339, 341, 
355; Bear valley, 302; Yir weir, 78. 

Deherain, 276. 

Delaware river water, 252. 

Denitrification, 334, 370; in sewage, 403; 
lessened by drainage, 420. 

Denmark, irrigation, 75. 

De Vries, 277. 

Divisors, 244. 

Ditches, depth and grade, 477 ; bringing 
to grade, 484 ; digging, 481 ; com- 
mencing and finishing,483 ; filling,487. 

Doon, for lifting water, 328. 

Drainage, principles, 415 ; influence on 
fertility, 13; remedy for alkali lands, 
284, 288; made necessary by seepage 
from canals, 295; of water-meadows, 
360, 364; of cranberry marshes, 366, 
368; rice fields, 369, 371; necessity, 
416; ventilates soil, 418, 419; lessens 
denitrification, 420; increases avail- 
able moisture, 13, 422 ; makes soil 
warmer, 423 ; where needed, 428 ; 
sinks and ponds, 460 ; intercepting 
underflow, 459; intercepting siirface 
water, 461; use of trees, 462 ; use of 
windmill, 463; levels, 470; tools, 482; 
peat lands, 491. 

Drainage levels, 470 ; use, 471, 473, 477. 

Drainage, surface, 464, 466. 

Drains, depth, 436, 442 ; distance apart, 
437, 439 ; used in sub-irrigation, 400; 
entrance of water, 438, 445 ; kinds, 
443 ; rate of entrance of water, 446 ; 
use of collars, 446 ; fall or gradient, 
447 ; size of mains, 450, 452 ; size of 
laterals, 450, 452 ; outlets, 453 ; ob- 
sti-uctions, 455 ; laying out systems, 



Index 



495 



456 ; cost, 458, 489 ; staking out, 476 ; 
determining depth and grade, 477 ; 
changing grade, 481 ; in peat lands, 
491; surface, 464, 466. 

Drill, seed, 167. 

Drought, frequency and length of pe- 
riods, 106, 108, 109, 126. 

Durance, fertility of water, 260 ; head- 
gate, 263. 

Duty of water, 212, 213, 214, 236 ; maxi- 
mum, 196 ; least amount for paying 
crop, 95; average, 214 ; highest prob- 
able, 198, 215; influenced by crop, 199, 
227 ; influenced by soil, 200, 203 ; in. 
fluenced by rainfall, 204 ; influenced 
i.by stibsoil, 205; influenced by cultiva- 
tion, 206 ; influenced by closeness of 
planting, 207; influenced by fertility, 
207 ; influenced by freqiiency of wa- 
tering, 207 ; in Egypt, 211 ; France, 
211; Italy, 209; Spain, 211; for sugar 
cane, 214 ; rice, 217; for water-mead- 
ows, 219 ; for cranberries, 220 ; in 
sub-irrigation, 396, 400. 

Di-y farming, western United States, 100. 

Dykes, 261, 306, 366, 369, 428 ; sluices 
373. 

Earthworms, in soil ventilation, 419. 

Ebermayer, temperature in germina- 
tion, 248, 425. 

Edinburgh, sewage irrigation, 92, 254, 
403; Evening Dispatch, 257. 

Egj-pt, irrigation, 67, 84, 260, 262, 328 ; 
duty of water, 211 ; prevention of 
alkali, 288. 

Elliott, C. G., 450, 451, 489, 490. 

England, irrigation, 76, 360, 409, 411, 
413. 

Euphrates, canals, 68. 

Evaporation, from plants, 40, 42 ; from 
clover field, 50; rate from soil, 98, 
148 ; from rolled ground, 167 ; in- 
influenced by windbreaks, 169 ; 
through mulches, 201. 



Fallowing, relation to soil moisture, 
153, 162, 163, 223. 

Fertility, influenced by drainage, 13 ; 
by cultivation, 370 ; affects duty of 
water, 207. 

Fertilization, by irrigation, IG, 92, 2"1, 
259. 

Fertilizers, in sewage, 404; in river wa- 
ter, 252, 253, 259, 260. 

Field irrigation, by flooding, 338, 345 ; 
in checks, 347, 350 ; by furrows, 352, 
354, 358; sub-irrigation, 399. 

Filtration of sewage, 404. 

Flume box, 375. 

Flynn, duty of water, 212. 

Flooding, 338; dry soil, 333 ; danger of 
puddling, 335; systems, 340 ; by run- 
ning water, 340; on steep slopes, 342; 
permanent meadows, 344 ; in checks, 
345, 347,350; preparatory to planting, 
353; to prevent frost, 365; to destroy 
insects, 365; rice fields, 369; to germi- 
nate red rice, 371; orchards, 383; gar- 
dens, 386, 390; lawns and parks, 392. 

Foot ditch, 378. 

Foote, A. D., spillbox, 245. 

Forez canal, 72. 

France, irrigation, |72' ; duty of water, 
211; water-meadows, 219. 

Fruit, irrigation, 383. 

Furrows, capillary spreading, 161, 330 ; 
distance apart, 336 ; gradient, 338 ; 
distributing, 340, 342. 

Furrow irrigation, 352, 358; on sandy 
soil, 330 ; on fine soil, 332 ; puddles 
soil less, 336; on steep slopes, 338 ; 
for potatoes, 354 ; in alternate rows, 
354, 357 ; for bed flooding, 359 ; for 
orchards, 375; ring-furrows, 380 ; for 
small fruits, 383 ; for gardens, 385, 
387, 389 ; for melons, 388 ; requires 
less water, 387. 

Garden,, irrigation, 384; sewage garden, 

407. 
Gas-engine, 324; cost of riinning, 324. 



496 



Index 



Gasoline engine, 305, 324, 393 ; cost of 
running, 324. 

Gasparin, ratio of grain to straw,l96 ; 
salt in soil, 276. 

Gennevilliers, sewage irrigation, 389, 
411; model gardens, 408 ; sewage hy- 
drant, 410 ; stone canal, 410 ; liealth- 
fulness, 413. 

Gipps, F. S., 66. 

Goff, E. S., irrigation of strawberries, 
181; depth of roots, 231. 

Goodale, G. A., 51. 

Goss, Arthur, 253, 259. 

Grade pegs, 478. 

Grader, 350, 351, 352. 

Grading for irrigation, 346, 348, 351. 

Grain, ii-rigation, 340, 342, 344, 346 ; dry 
farming, 103 ; harrowing and rolling, 
146 ; thin seeding, 163 ; di;ty of water, 
198. 

Grapes, roots, 232; frequency of irriga- 
tion, 238. 

Grass, observed yields, 127; on sewage 
meadows, 92, 409; on water-meadows, 
219 ; irrigation, 340, 342, 346 ; in lawns 
and parks, 392. 

Gravel, silted, 263. 

Greeley, Colorado, irrigation of grain, 
340 ; potatoes, 354. 

Green manure, 151. 

Ground-water, origin, 429 ; relation to 
surface, 431, 435 ; lines of flow, 432, 
438 ; discharge into streams, 433 ; 
gradient, 435; changes in level, 440. 

Growth of river, 433. 

Grunsky, C. E., 292, 349. 

Hall, Wm. H., 211. 

Hare, R.F., 253. 

Harrington, M. W., 99. 

Harvey, F. H., 309. 

Hawaii, irrigation, 86 ; duty of water 
for sugar cane, 214. 

Hay, yields, 127, 178 ; need for irriga- 
tion, 128 ; second crop, 130, 179 ; duty 
of water, 215. 



Hazzard, W. M., rice irrigation, 238. 
Health, influence of sewage, 256, 295, 
Heilriegel, 96. [413. 

HCgard, E. W., peculiarities of arid 

soils, 6, 229 ; alkali lands, 269, 276 ; 

composition of alkali salts, 278 ; land 

plaster for alkali lands, 280,284; roots 

in arid soils, 6, 229. 
Hinton, R. J., 78, 81. 
Hollis, Geo. S., 85. 
Humidity of air, 40, 44, 50. 
Hunter, intertillage, 157. [410. 

Hydrants, distributing, 301 ; sewage, 
Hydraulic rams, 310. 

Inch, acre, 240; miner's, 241, [291. 

India, irrigation, 77, 328; Sirhind canal. 

Insects, destroyed by irrigation, 218, 221. 

Intertillage, 157. 

Irrigation culture, 66. 

Irrigation, antiquity, 66; extent, 72; ob- 
jects, 91; climatic conditions, 89; fre- 
quency, 107, 212, 223, 234, 236 ; insuf- 
fiency of water, 117 ; amount of water, 
196, 208, 212, 213, 214, 236 ; late crops 
difficult to grow without, 129 ; in- 
crease of yield in humid climates, 171; 
closer planting possible, 181 ; tillage 
as a substitute, 117 ; character of 
water, 248 ; temperature, 248 ; num- 
ber of irrigations required, 235; fer- 
tilizing value, 251 ; supplying water, 
290 ; methods of application, 329 ; 
sewage, 403. 

Italy, irrigation, 71, 359; duty of water, 
209, 219 ; water-meadows, 219 ; mar- 
cite, 219 ; sewage, 220. 

Ivrea canal, 209. • 



Japan, irrigation, 82. 
Java, irrigation, 86. 



m 



Kansas, yields of grain, 103; rainfall, v 

103. 
Kern Island canal, 292. 
Kiihn, Jul., 454. 



Index 



497 



Land plaster, for alkalies, 280, 284, 287. 

Laterals, subdivision, 228; length, and 
size, 452 ; outlet, 454; jimetion, 464; 
cost, 490. 

La-\yn, irrigation, 391 ; cost of plant, 393; 
method, 395. 

Laveleye, E.,75. 

Leaching, 222; may assist nitrification, 
12; prevents alkali, 223, 284, 288; nec- 
essary, 275. 

Leveling, methods, 471,473, 477. 

Levels, methods, 469; instruments, 470. 

Lois Weedon, system of intertillage,157. 

Lombardini, 260. 

Lombock, irrigation, 87. 

Lettuce, irrigation, 385. 

Lew Chew, irrigation, 83. 

Loughridge, R. H., 229. 

Madagascar, irrigation, 86. 

Madeira, irrigation, 86. 

Maeris, Lake, 66. 

Mains, 451, 457; size, 451; length, 452; 
cost, 490. 

Maize, water used, 21, 24, 38, 39, 41, 46, 
60, 177, 234 ; flint and dent, 40, 184; 
roots, 61, 160; yields and rainfall, 109; 
yield increased by irrigation, 110, 177; 
observed yields, 126, 177, 190; varia- 
tion of yield with soil moistiire, 144; 
rain of growing season, 124 ; maxi- 
mum limit of yield, 187; need for air, 
182,185; close planting, 184,193; yields 
with varying closeness of planting, 
190; duty of water, 211, 215; frequency 
of irrigation, 235. 

Mangon, water on water-meadows, 219. 

Marcite, 219. 

Markus, E., duty of water, 203. 

Meadows, water, 16, 92, 219, 251, 359; 
Craigentinny, 16, 92, 254, 403; English, 
76, 360; Italian, 362; Belgian, 362; 
mountain, 365; marcite, 219; duty of 
water, 219; sewage, 220, 254; mulch- 
ing, 146; irrigation, frequency, 237. 

Measurement of water, 239; units, 239; 



methods, 241; by time, 242; subdivi- 
sion of laterals, 243 ; with divisors, 
244; modules, 245. 

Melons, irrigation, 388. 

Milan, sewage irrigation, 220. 

Milk, from sewage grass, 256. 

Miner's inch, 241. 

Mississippi, annual discharge, 117. 

Modules, 245; spill-box, 245, 

Mulches, 145; of soil, 142; effectiveness 
in ai'id climates, 104; lose effective- 
ness, 145, 164; for meadows, 146; in- 
fluence of depth, 147, 200; vary with 
kinds of soil, 201; production after 
irrigation, 381. 

Neerpelt, water-meadows, 362. 

Newell, F. H., irrigation, 88; dry farm- 
ing, 102; run-off, 119. 

New Jersey, water analyses, 252. 

New Mexico, frequency of irrigation, 
238. 

Nile, irrigation, 67, 84, 262, 288; daily 
discharge, 85; delta, 68; sediment in 
water, 260. 

Nitrates, in artesian waters, 85 ; in 
river water, 252; in sewage, 404. 

Nitrification, in arid soils, 7; needs wa- 
ter, 11 ; influenced by drainage, 13, 
420; effect of tillage, 149, 163, 165; 
needs oxygen, 183, 384, 370, 418. 

Nitrogen-fixing tubercles^ 233. 

Oats, water used, 21, 24, 31^ 41, 46; rain 

of growing season, 124; yields, 126; 

water needed, 215. 
Oranges, frequency of irrigation, 238; 

furrow irrigation, 374. 
Orchards, irrigation, 388, 373; frequency 

of irrigation, 238; ring furrows, 880; 

cultivator, 381; cultivation, 881, 388; 

sub-irrigation, 398. 
Osmotic pressure, 68. 

Pa?cottah, 327. 
Palms, irrigation, 85. 



4.98 



Index 



Park irrigation, 391. 

Peas, water used, 46. 

Peat lands, 491; warping, 262. 

Percolation of water, 225 ; through 
sand, 113, 205; on duty of water, 203; 
through shrinkage cracks, 227 ; into 
tile, 446; loss, 330; rate from tile, 400. 

Perels, E., duty of water, 203, 212. 

Persian wheel, 325, 328. 

Peru, irrigation, 71. 

Phoenician irrigation, 69. [299. 

Pipe line, Redlands, 296; redwood, 298, 

Pipes for lawns, 394. 

PJaguiol, salt in soils, 275. 

Plant breathing, 47. 

Plant feeding, 52, 57. 

Plant-food, 14, 15, 93, 252, 259 ; developed 
by tillage, 149; effect of fallowing, 
154; in alkali salts, 280, 285. 

Plant-house experiments, 18, 35, 43; 
yields, 25, 41. 

Plowing, fall, 131; plowing under green 
manure, 151; to form check ridges, 
346. 

Plow, for producing miilch, 149 ; for 
producing distributing fiu'rows, 340, 
342. [260. 

Po, irrigation, 72; sediment in water. 

Potatoes, ii-rigation, 28, 32, 35, 172, 353, 
357, 413; water used, 30, 37, 46, 174. 
237; yields, 110, 357; advantages of 
irrigation in humid climates, 172 ; 
watering alternate rows, 354, 357 ; 
distance between rows, 357; moisture 
in rows, 161, 200; duty of water, 215; 
number of waterings, 237, 356. 

Press drill, 167. 

Puddling of soils, principles governing, 
334. 

Pumping, with windmill, 313, 316; with 
engines, 324; cost, 324, 326; for cran- 
berries, 368 ; for drainage, 463. 

Pumps, with windmill, 316, 319; with 
engines, 324, 326, 393; with water 
wheels, 76, 306, 308, 309; with horse 
I)Ower, 325. 



Quicksand, 488. 

Rainfall, in arid and semi-arid climates, 
4,6,99,101; timely, 10; of irrigated 
countries, 89; in Kansas, 103; fre- 
quency in Wisconsin, 108 ; like 
amounts not equally effective, 101, 
115, 204 ; relation to yield, 109, 125 ; 
conditions modifying effectiveness, 
110; in United States, 123; in eastern 
United States, 124; amount needed in 
humid regions, 121; of growing sea- 
son, 124 ; distribution in time un- 
favorable to maximum yields, 125; 
early rains saved hj tillage, 128: af- 
fects duty of water, 204; in Colorado, 
236; in India, 291. 

Ramming engine, 310. 

Rape, irrigation, 359. 

Raspberries, roots, 231; irrigation, 383; 
sub-irrigation, 398. 

Read, T. M., solids in river waters, 253. 

Redlands, Cal., irrigation systems, 296. 

Red rice, 371. 

Reservoir, distributing, 297; construc- 
tion, 320; sluice, 321; circular, 322; 
seepage and evaporation, 323; capac- 
ities, 323; for cranberries, 367; use in 
drainage, 464. 

Rice, irrigation, 368; in Italy, 210; in 
Egypt, 211; South Carolina, 238, 266, 
306, 369, 372; duty of water, 217; fre- 
quency of irrigation, 238 ; ctiltiva- 
tion, 370; red rice, 371; upland, 373. 

Ridge cultivation, 165. 

Rio Grande, analyses of water, 253, 259. 

Road grader, 350. 

Rolling in relation to soil moisture, 166; 
cause of loss of moisture, 167. 

Roman canals, 70. 

Root cap, 64. 

Root hairs, 55; relation to soil grains, 
55; acid reaction, 59. 

Roots, depth of penetration in arid- 
soils, 6, 229; shallow in undrained 
soil, 13; function, 55; absorbing sur- 



Index 



499 



face, 55; acid reaction, 59; extent of 
siu-face, 59, 61, 160 ; movement 
through soil, 63; superficial develop- 
ment, 208; depth, 200, 227, 231; oats, 
clover and barley, 60; maize, 61; 
pi-une, 228; apple, 229; grape, 230; 
raspberry, 231 ; straAvberi-y, 232 ; 
alfalfa, 233. [119. 

Run-off, Mississippi, 117; United States, 

Rye as green manure, 151. 

Rye grass, for sewage meadows, 409. 

Sachs, 55, 425. 

Sahara, irrigation, 85. 

Salts, soluble in alkali land, 269, 276; 
cause of injuries, 270 ; accumulate 
with intensive farming, 274; amount 
injurious, 275, 278. 

Saltwirt, 276. 

Sandwich Islands, irrigation, 86; duty 
of water, 215. 

Sand, percolation, 112, 224. 

Sandy soils, experiments, 32; texture 
improved by irrigation, 93, 262; re- 
tain little water. 111, 205, 224 ; why 
unproductive, 114; destructive effects 
of winds, 168; areas suited to irriga- 
tion, 264; fm-row irrigation, 330, 358; 
handling water, 331. 

San Joaquin valley, 4, 96, 98; flooding 
system, 348. 

Scraper, ridging, 348, 351. 

Seaman and Schuske, bucket pump, 316. 

Second-foot, 239. 

Seed-bed, preparation, 150, 167. 

Seepage, coarse soils, 203; upland rice 
cvilture, 218 ; from canals, 244 ; from 
reservoirs, 323. 

Sewage, dangerous nitrogen com- 
pounds, 405; agrieultui-al value, 406; 
need of wider agricultural use, 406, 
409 ; in Italy, 406 ; Edinbm-gh, 403 ; 
Milan, 407; Paris, 407; Croyden, 411, 
412, 413. 

Sewage effluent, purity, 414; bacteria, 
414. 



Sewage grass, wholesomeness, 256, 413. 

Sewage irrigation, object sought, 403; 
Craigentinny meadows, 16, 92, 254; 
healthfulness, 256, 405, 413; distri- 
bution of water, 403; climatic condi- 
tions favorable, 404; report of Mas- 
sachusetts State Board of Health, 
405; soils best suited, 406; oppor- 
tvmity for in United States, 407; 
model garden, 407 ; yield of grass, 409 ; 
grasses for, 409; crops, 409, 411. 

Sewage purification, 405; by irrigation, 
405; by filtration, 404; essential con- 
ditions, 405. 

Sewage water, 15, 92, 220, 253. 

Siam, irrigation, 83. 

Silt basin, 448. 

Silting coarse soils, 93, 260, 261; oppor- 
tunity for in United States, 264; of 
rice fields, 370. 

Siphon, in pipe line, 296; elevator, 310. 

Sirhind canal, 291. 

Sluice, for reservoir, 261, 321, 369. 

Small fruits, irrigation, 383; late plow- 
ing, 132. 

Smith, Baird, duty of water, 209 ; water- 
meadows, 220. 

Smith, Rev., system of intertillage, 157. 

Smith, Brothers, irrigation plant, 308. 

Soil, water capacity, 3, 224; texture in 
relation to rainfall, 3; humid and 
arid, 4; ventilation, 11, 419; water- 
logging, 11, 334; sandy, 32, 111, 114, 
168, 205, 224, 264, 330, 331, 358; silt- 
ing, 93, 260, 262, 263, 264; midches, 
201, 206; black marsh, 201, 281; pore 
space, 63; best temperature, 248; 
alkali, 282; clay, 286; pviddling, prin- 
ciples governing, 334, 335 ; washing, 
principles governing, 337 ; absorp- 
tion of sewage, 404 ; kinds best 
suited to sewage irrigation, 406. 

Soil grains, relation to root hairs, 55; 
relation of size to drainage, 438. 

Soil mulches, 142; more effective in 
arid climates, 105; effectiveness, 144, 



500 



Index 



201 ; lose effectiveness, 145 ; of dif- 
fei-ent soils compared, 144, 201 ; 
depth, 147, 165, 206; frequency of stir- 
ring, 164. 

Soil moisture, advantages of abundant 
supply, 9; mechanism of plant sup- 
ply, 54; effect of subsoiling, 134; ef- 
fect of fallowing, 153, 155, 162, 225; in 
potato rows, 161; means of conserv- 
ing, 131; conservation by tillage, 164; 
influence of rolling, 166; loss through 
mulches, 144, 201; best amount, 226. 

Soil ventilation, 419; need, 11; work of 
carbonic acid, 419; influence of drain- 
age, 418; part played by roots, 420, 
421; infliience of changing air tem- 
perature and pressure, 420; may les- 
sen denitrification, 420; may increase 
nitrates, 420; may be too thorough, 
421. 

Soil temperature, 248, 250, 425; in- 
fluenced by drainage, 423 ; importance, 
425; influence on germination, 425; 
influence of cultivation, 427. 

Soil warmth, 425. 

Soil water, plant-food dissolved, 14 ; 
amount of alkalies carried, 278; stag- 
nation prevented by drainage, 416. 

South America, irrigation, 87. 

South Carolina, rice irrigation, 238, 
266, 306, 369, 372. 

Spain, irrigation, 72, 238 ; duty of water, 
211. 

Spill-box, 245. 

Spraying lawns, 393. 

Strawberries, irrigation, 110, 181, 384 ; 
roots, 232; sub-irrigation, 398. 

Storer, F. H., 254, 275. 

Sub-irrigation, 396; of clover, 179; ob- 
jections and difficulties in the way, 
396, 397, 401 ; water-meadows, 401 ; 
orchards and small fruits, 401 ; dan- 
ger of clogging tile by roots, 401 ; 
time required, 401 ; through tile 
drains, 400; conditions necessary, 401; 
an adjunct to drainage, 460. 



Subsoil, affects duty of water, 205. 

Subsoiling, 133 ; effects, 139 ; sugar 
cane, irrigation, 214 ; duty of water, 
215. 

Summer fallowing, 153, 154, 163. 

Sunlight, evaporation during, 44; action 
in plant-feeding, 49; limited in close 
planting, 183, 194. 

Surface drainage, 464 ; examples, 466 ; 
peat lauds, 491. 

Sui'faee tension, 57. 

Swamp lands, 273 ; area in United 
States, 415 ; improved by drainage, 
416 ; intercepting underflow, 459 ; in- 
tercepting surface water, 461. « 

Switzerland, irrigation, 74, 365. 

Target-rod, 470, 471. 

Temperature of soil, 248 ; subsoil 
changed by rains and irrigation, 14, 
218 ; reduced by close planting, 183 ; 
favorable to sewage irrigation, 404. 

Temperature of water for irrigation, 
250. 

Tidal irrigation, 238, 261, 306, 369, 373. 

Tigris, canals, 69. 

Tile, injui-y by frost, 442 ; for sub-irri- 
gation, 398, 400; size, 449, 452; laying, 
484; in quicksand, 488. 

Tile-hook, 482. 

Tillage, extent to which it may replace 
rain or irrigation, 117 ; most which 
may be hoped for tillage, 120 ; inap- 
plicable in some cases, 127 ; chiefly 
saves early rains, 128; may do harm, 
129 ; late plowing, 132 ; subsoiling, 
133; earth mxilches, 142, 164, 206; 
mulches lose in effectiveness, 145 ; 
harrowing and rolling, 146, 166; early 
tillage important, 148 ; plow as a til- 
lage tool, 149 ; intertillage, 157, 163 ; 
frequency of tillage, 164, 205 ; depth, 
165, 206 ; ridged and flat cultivation, 
165 ; in rice fields, 370 ; after irriga- 
tion, 381, 389 ; with orchard cultiva- 
tor, 381. 



Index 



501 



Time as a unit for division of water, 

242. 
Transpiration, greatest during sun- 

sliine, 45, 46 ; need of water, 50 ; 

mechanism, 46; metliod, 46 ; control' 

53. 
Tulare Exp. Station, 276. 
Tull, Jethro, system of intertillage, 157. 
Turbine wheel, 308. 
Underdraining, practical details, 467 ; 

cost, 489; peat lands, 491. 

Underflow, intercepting, 459. 
Underground water, diverting for irri- 
gation, 304. 
Units of water measurement, 239. 

Vegetables, garden irrigation, 385. 
Ventilation of soil, 419. See soil venti- 
lation. 
Vir weir, 78. 
Vosges, water-meadows, 219. 

Warping, 94, 261. 

Washing of soil, principles governing, 
337. 

Washington, dry farming, 100; rainfall, 
101, 204. 

Water, apparent greater service in arid 
climates, 5, 104; need for nitrifica- 
tion, 12; fertilizing value, 14, 93, 251' 
259; only one of the necessary plant 
foods, 15; amount used by crops, 16 
21, 24, 30, 36, 37, 38, 39, 41, 46, 60, 97, 122, 
160, 174, 177, 215; variations in amount 
used by crops, 39; used in transpira- 
tion, 50; action in plant feeding, 58; 
amount needed for given crop, 87; 
least amount for paying crop, 95; least 
amount in soil which permits growth, 
111, 225; retained by sand, 114, 224; 
insufficiency for irrigation, 117; in 
subsoiled ground, 136; lost through 
mulches, 142, 20] ; lost from wet soil, 
148; in fallow gi'ound, 155, 225; capil- 
lary spreading, 161, 330, 377; conserved 



by tillage, 164, 353 ; importance of 
amount and distribution in potato 
culture, 172; duty, 196 (see Duty of 
water) ; amount for single irrigation, 
222, 223, 225, 227, 234 ; capacity of soils, 
224, 353; best amount for crops, 227; 
measurement, 239; cold, for irriga- 
tion, 249; value of turbid, for irriga- 
tion, 259; alkali waters, 267, 268, 284, 
285, 287; supplying, for irrigation, 290; 
methods of applying, 329; loss by per- 
colation, 330; rate of application, 331, 
332, 337; depth in flooding, 346; 
amount needed for lawns and parks, 
392 ; amount needed for sub-irriga- 
tion, 397, 401. 

Water level, 416. 

Water-logged soil, 11, 334. 

Water-meadows, 16, 92, 219, 251, 3.59 ; 
English, 76, 360; use of sewage, 220, 
254, 403, 409; frequency of irrigation, 
237; Belgian, 362; Italian, 362; moun- 
tain, 74, 365. 

Water supply, for irrigation wells, 78, 
84, 85, 86, 251, 393 ; from rivers, 290; 
underground waters, 304; lifting by 
water-power, 306; storm water, 311; 
by wind power, 312; by engines, 324, 
326; cost, 324; by animal power, 325, 
328; for cranberries, 367. 

Water wheels, 75, 306, 308. 

Weiss, number of breathing pores, 51. 

Wells, for irrigation, 78, 84, 251, 393; in 
Algeria, 85; in Hawaii, 86; for lawns 
and gardens, 393. 

Wheat, ratio of grain to straw, 96; 
water used, 97, 101, 215; intertillage, 
158 ; frequency of irrigation, 235. 

Willcocks, W., EgjT)tian irrigation, 84, 

F 211 ; cost of pumping, 326. 

Wilson, H. M., area of land irrigated, 
88; duty of water, 211; liftijig water, 
309, 311, 325, 327. 

Winds, lessening destructive effects, 
168. 

Windbreaks, 169. 



502 



Index 



Windmills, conditions for highest ser- 
vice, 318; for lifting water, 312, 316, 
318, 367; capacity for irrigation, 318; 
use in drainage, 463. 



Wind power, for irrigation, 312; work 
done by months, 315; work done by 
10-day periods, 316. 

Wolff, A. R., 318. 



• 



3477 4 




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